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A network of co-hepato/pancreatic stem/progenitors exists postnatally in the intrahepatic, extrahepatic and intrapancreatic biliary trees of pigs and humans and found to support hepatic and pancreatic regeneration throughout life. The stem/progenitors have genetic signatures in liver/pancreas-related RNA-seq data based on Correlation, hierarchical clustering, KEGG and Short Time-series Expression Miner (STEM) analyses. Representative phenotypic traits are expression of pluripotency genes (SOX2, OCT4, KLF4), endodermal transcription factors (SOX9, SOX17, PDX1, NGN3), other stem cell traits (NCAM, EpCAM, BMI-1, CD44), and proliferation biomarkers (Ki67). Stem/progenitor niches in vivo are in peribiliary glands (PBGs) throughout the intrahepatic and extrahepatic biliary tree, in duodenal submucosal glands (Brunner’s Glands), and in pancreatic duct glands (PDGs). The highest numbers of niches in humans are in PBGs in the hepato/pancreatic common duct, a duct missing in pigs; by contrast, the highest numbers in pigs are in Brunner’s Glands and in a subset of PDGS, those nearest to the duodenum. Elsewhere in PDGs in the porcine pancreas, and in all PDGs in the human pancreas, are found only committed unipotent and bipotent progenitors. Multipotentiality of the stem/progenitors was indicated by their ability to yield hepatic versus pancreatic fates under distinct ex vivo conditions or in vivo when organoids of them were transplanted onto liver versus pancreas using patch grafting strategies. The findings establish pigs as logical hosts for translational/preclinical studies assessing grafts of organoids of the biliary tree’s co-hepato/pancreatic stem cells as cell therapies for diseases and dysfunctions in liver and pancreas both for humans and for veterinary animals.

Patch grafting, a novel strategy for transplantation of stem/progenitor organoids into porcine livers, has been found successful also for organoid transplantation into other normal or diseased solid organs in pigs and mice. Each organoid contained ∼100 cells comprised of biliary tree stem cells (BTSCs), co-hepato/pancreatic stem/progenitors, and partnered with early lineage stage mesenchymal cells (ELSMCs), angioblasts and precursors to endothelia and stellate cells. Patch grafting enabled transplantation into livers or pancreases of ≥10

The main objective of this book is to present a thorough update on stem cell research and the potential therapeutic applications of stem cells. The text is structured following a path that starts from the molecular basics and the biological properties of pluripotent, embryonic or reprogrammed stem cells, and it compares the different degrees of stemness, while describing the adult stem populations residing in the various tissues and organs of the human body. Starting from basic research, the book discusses examples of regenerative medicine that translate the experimental findings into clinical applications of cell therapy. Finally, the book reviews how stem cells represent a model to understand not only the physiological mechanisms that control their fate, but also the pathological mechanisms involved in the aberrant biology of cancer stem cells. Each chapter has been conceived by distinguished researchers in the field who provide detailed and updated contributions that distill knowledge in a very readable text. Laura Bonsi is Associate Professor of Histology at the Department of Experimental, Diagnostic and Specialty Medicine of the University of Bologna. Francesco Alviano is Assistant Professor of Histology at the Department of Experimental, Diagnostic and Specialty Medicine of the University of Bologna. Prof. Bonsi and Dr. Alviano are authors of numerous scientific papers published in international journals. They coordinate the Biotechnology Laboratory of Human Stem Cells at the University of Bologna, that is focused on the study of stem cells isolated from different sources, above all from extraembryonic tissues such as the placenta, the umbilical cord, and the fetal membranes. They are longterm members of the International Placenta Stem Cell Society (IPLASS).

Significance The existence of progenitors within pancreatic ducts has been studied for decades, but the hypothesis that they may help regenerate the adult endocrine compartment (chiefly insulin-producing β-cells) remains contentious. Here, we examine the single-cell transcriptome of the human ductal tree. Our data confirm the paradigm-shifting notion that specific lineages, long thought to be cast in stone, are in fact in a state of flux between differentiation stages. In addition to pro-ductal and pro-acinar transcriptomic gradients, our analysis suggests the existence of a third (ducto-endocrine) differentiation axis. Such prediction was experimentally validated by transplanting sorted progenitor-like cells, which revealed their tri-lineage differentiation potential. Our findings further indicate that progenitors might be activated in situ for therapeutic purposes., We have described multipotent progenitor-like cells within the major pancreatic ducts (MPDs) of the human pancreas. They express PDX1, its surrogate surface marker P2RY1, and the bone morphogenetic protein (BMP) receptor 1A (BMPR1A)/activin-like kinase 3 (ALK3), but not carbonic anhydrase II (CAII). Here we report the single-cell RNA sequencing (scRNA-seq) of ALK3bright+-sorted ductal cells, a fraction that harbors BMP-responsive progenitor-like cells. Our analysis unveiled the existence of multiple subpopulations along two major axes, one that encompasses a gradient of ductal cell differentiation stages, and another featuring cells with transitional phenotypes toward acinar tissue. A third potential ducto-endocrine axis is revealed upon integration of the ALK3bright+ dataset with a single-cell whole-pancreas transcriptome. When transplanted into immunodeficient mice, P2RY1+/ALK3bright+ populations (enriched in PDX1+/ALK3+/CAII− cells) differentiate into all pancreatic lineages, including functional β-cells. This process is accelerated when hosts are treated systemically with an ALK3 agonist. We found PDX1+/ALK3+/CAII− progenitor-like cells in the MPDs of types 1 and 2 diabetes donors, regardless of the duration of the disease. Our findings open the door to the pharmacological activation of progenitor cells in situ.

Acute respiratory distress syndrome (ARDS) in COVID-19 is associated with high mortality. Mesenchymal stem cells are known to exert immunomodulatory and anti-inflammatory effects and could yield beneficial effects in COVID-19 ARDS. The objective of this study was to determine safety and explore efficacy of umbilical cord mesenchymal stem cell (UC-MSC) infusions in subjects with COVID-19 ARDS. A double-blind, phase 1/2a, randomized, controlled trial was performed. Randomization and stratification by ARDS severity was used to foster balance among groups. All subjects were analyzed under intention to treat design. Twenty-four subjects were randomized 1:1 to either UC-MSC treatment (n = 12) or the control group (n = 12). Subjects in the UC-MSC treatment group received two intravenous infusions (at day 0 and 3) of 100 ± 20 × 106 UC-MSCs; controls received two infusions of vehicle solution. Both groups received best standard of care. Primary endpoint was safety (adverse events [AEs]) within 6 hours; cardiac arrest or death within 24 hours postinfusion). Secondary endpoints included patient survival at 31 days after the first infusion and time to recovery. No difference was observed between groups in infusion-associated AEs. No serious adverse events (SAEs) were observed related to UC-MSC infusions. UC-MSC infusions in COVID-19 ARDS were found to be safe. Inflammatory cytokines were significantly decreased in UC-MSC-treated subjects at day 6. Treatment was associated with significantly improved patient survival (91% vs 42%, P = .015), SAE-free survival (P = .008), and time to recovery (P = .03). UC-MSC infusions are safe and could be beneficial in treating subjects with COVID-19 ARDS.

Pancreatic islet cells, and in particular insulin-producing beta cells, are centrally involved in the pathogenesis of diabetes mellitus. These cells are of paramount importance for the endocrine control of glycemia and glucose metabolism. In Type 1 Diabetes, islet beta cells are lost due to an autoimmune attack. In Type 2 Diabetes, beta cells become dysfunctional and insufficient to counterbalance insulin resistance in peripheral tissues. Therapeutic agents have been developed to support the function of islet cells, as well as to inhibit deleterious immune responses and inflammation. Most of these agents have undesired effects due to systemic administration and off-target effects. Typically, only a small fraction of therapeutic agent reaches the desired niche in the pancreas. Because islets and their beta cells are scattered throughout the pancreas, access to the niche is limited. Targeted delivery to pancreatic islets could dramatically improve the therapeutic effect, lower the dose requirements, and lower the side effects of agents administered systemically. Targeted delivery is especially relevant for those therapeutics for which the manufacturing is difficult and costly, such as cells, exosomes, and microvesicles. Along with therapeutic agents, imaging reagents intended to quantify the beta cell mass could benefit from targeted delivery. Several methods have been developed to improve the delivery of agents to pancreatic islets. Intra-arterial administration in the pancreatic artery is a promising surgical approach, but it has inherent risks. Targeted delivery strategies have been developed based on ligands for cell surface molecules specific to islet cells or inflamed vascular endothelial cells. Delivery methods range from nanocarriers and vectors to deliver pharmacological agents to viral and non-viral vectors for the delivery of genetic constructs. Several strategies demonstrated enhanced therapeutic effects in diabetes with lower amounts of therapeutic agents and lower off-target side effects. Microvesicles, exosomes, polymer-based vectors, and nanocarriers are gaining popularity for targeted delivery. Notably, liposomes, lipid-assisted nanocarriers, and cationic polymers can be bioengineered to be immune-evasive, and their advantages to transport cargos into target cells make them appealing for pancreatic islet-targeted delivery. Viral vectors have become prominent tools for targeted gene delivery. In this review, we discuss the latest strategies for targeted delivery of therapeutic agents and imaging reagents to pancreatic islet cells.

Background & Aim: Mesenchymal stem cells (MSCs) have been shown to modulate hyperinflammation, promote tissue repair and secrete antimicrobial factors. MSCs have been studied in clinical trials of autoimmune diseases, inflammatory disorders, refractory GvHD and acute respiratory distress syndrome (ARDS). MSCs can be isolated and expanded from multiple tissues, including umbilical cord (UC). A number of clinical studies demonstrated safety and feasibility of UCMSCs therapy for the treatment of COVID-19 ARDS. UC-derived MSCs are easily available and can be quickly expanded to relevant numbers. UC-MSCs have an extended population doubling capacity and express low levels of class I and class II leukocyte antigen, which may reduce alloreactivity. To meet clinical manufacture demands, UC-MSC production requires an innovative, scaled-up manufacturing platform. We describe the manufacturing strategy developed in support of a double-blind, randomized, controlled UC- MSC clinical trial in subjects with COVID-19 ARDS. Methods, Results & Conclusion: UC-MSC Final Product was manufactured from the master cell bank (MCB) derived from subepithelial lining of a UC from a healthy term delivery, in cGMP conditions. Utilizing a 2D culture xenogeneic protein-free process, UC-MSC MCB was culture-expanded during 3 expansion cycles, in tissue culture treated vessels with increased surface area for each expansion, in commercially available tissue culture media supplemented with platelet lysate. Cells were harvested during log phase, at 75-80% confluence. The manufacturing process yielded ~ 300x increase in total viable cells at the end of the last expansion cycle. The Final Product was cryopreserved using a controlled rate freezer. Each subject in the treatment group received two doses of 100×106 UC-MSCs. A single UC-MSC Final Product batch was sufficient to treat all subjects randomized to the treatment group and complete the trial. The final product was tested for identity (label verification), effectiveness by viable cell dose and cell viability (>80%), safety by assessment of endotoxin ( 90%, CD34/CD45

Here we review the characteristics of human pancreatic progenitors, from those that give rise to the different lineages of the pancreas during embryonic development to the cells that have been associated with regenerative processes in adulthood. In the first part of this chapter, we dissect the critical steps that dictate the specification of exocrine and endocrine cell types during pancreatic development, with a special focus on the maturation of pancreatic islet endocrine cells. The second part zeroes in on the highly debated existence and potency of putative progenitor cells in the adult pancreas. The importance of this topic is highlighted by the potential clinical applications of pancreatic progenitor cells for metabolic conditions affecting the endocrine compartment of the pancreas. With 400 million people affected by diabetes mellitus worldwide, the search for a sustainable source of functional insulin-producing cells represents a major driving force in this area of investigation. Challenging questions that continue to agitate the field are discussed for the reader in the last section of this chapter: can the adult pancreas and pancreatic islet cells regenerate? Do transdifferentiation and plasticity play a role? Can we generate true beta cells from stem and progenitor cells?

Background: Acute Respiratory Distress Syndrome (ARDS) in COVID-19 is associated with high mortality. Mesenchymal Stem Cells (MSC) are potent immunomodulatory cells. The aim of this study was to determine safety and explore efficacy of Umbilical Cord (UC)-MSC infusions in COVID-19 ARDS. Methods: A double-blind, phase 1/2a, randomized, controlled trial was performed in subjects with ARDS secondary to COVID-19, at a single institution in Miami, Florida, USA. Randomization and stratification by ARDS severity was used to foster balance among groups. Participants received two intravenous infusions of 100x106 UC-MSC, or vehicle, at day 0 and 3. The primary endpoint was safety, defined by occurrence of pre-specified infusion associated adverse events, along with adverse events during 28 day follow-up. All subjects were analyzed under an intention to treat design. Exploratory efficacy endpoints included survival at 28 days and time to recovery. Findings: 24 subjects (12 per group) were recruited between April 25 and July 21 2020. At 28 days post last infusion, patient survival was 91% and 42% in the UC-MSC and Control groups, respectively (p=0.015). No serious adverse events (SAEs) were observed related to UC-MSC infusions. There was no observed difference in number of subjects experiencing infusion-associated adverse events. Treatment unrelated SAEs were reported in 2 and 8 patients in the UC-MSC and Control groups, respectively (p=0.04). UC-MSC treatment was associated with increased SAE-free survival (p=0.008) and decreased time to recovery (p=0.03) compared to controls. Interpretation: UC-MSC infusions in COVID-19 subjects with ARDS were safe and associated with fewer SAEs, compared to control. Further, exploratory efficacy analyses provide preliminary evidence of reduction in mortality and time to recovery. Notwithstanding sample size limitations of this trial, the observed findings strongly support further investigation in a larger trial designed to estimate and test for efficacy. Trial Registration: (ClinicalTrials.gov NCT04355728). Funding Statement: The trial was funded by the Barilla Group and Family, The Cure Alliance, the Fondazione Silvio Tronchetti Provera, the Simkins Family Foundation, the North America’s Building Trades Unions, and the Diabetes Research Institute Foundation. This publication was supported by the Clinical Translational Research Site Grants Number UL1TR000460 and UL1TR002736 from the National Center for Advancing Translational Sciences (NCATS). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: Ethics Committee Approval by the regulatory and institutional review boards were obtained by the Western Institutional Review Board (WIRB) and UM Human Subject Research Office/Institutional Review Board, in accordance with local institutional requirements.

We have described multipotent progenitor-like cells within the major pancreatic ducts (MPDs) of the human pancreas. They express PDX1, its surrogate surface marker P2RY1, and the bone morphogenetic protein (BMP) receptor 1A (BMPR1A)/activin-like kinase 3 (ALK3), but not carbonic anhydrase II (CAII). Here we report the single-cell RNA sequencing (scRNA-seq) of ALK3 bright+ -sorted ductal cells, a fraction that harbors BMP-responsive progenitor-like cells. Our analysis unveiled the existence of multiple subpopulations along two major axes, one that encompasses a gradient of ductal cell differentiation stages, and another featuring cells with transitional phenotypes toward acinar tissue. A third potential ducto-endocrine axis is revealed upon integration of the ALK3 bright+ dataset with a single-cell whole-pancreas transcriptome. When transplanted into immunodeficient mice, P2RY1 + /ALK3 bright+ populations (enriched in PDX1 + /ALK3 + /CAII − cells) differentiate into all pancreatic lineages, including functional β-cells. This process is accelerated when hosts are treated systemically with an ALK3 agonist. We found PDX1 + /ALK3 + /CAII − progenitor-like cells in the MPDs of types 1 and 2 diabetes donors, regardless of the duration of the disease. Our findings open the door to the pharmacological activation of progenitor cells in situ.

Purpose of Review Hyperexpression of classical HLA class I (HLA-I) molecules in insulin-containing islets has become a widely accepted hallmark of type 1 diabetes pathology. In comparison, relatively little is known about the expression, function and role of non-classical subtypes of HLA-I. This review focuses on the current understanding of the non-classical HLA-I subtypes: HLA-E, HLA-F and HLA-G, within and outside the field of type 1 diabetes, and considers the possible impacts of these molecules on disease etiology. Recent Findings Evidence is growing to suggest that non-classical HLA-I proteins are upregulated, both at the RNA and protein levels in the pancreas of individuals with recent-onset type 1 diabetes. Moreover, associations between non-classical HLA-I genotypes and age at onset of type 1 diabetes have been reported in some studies. As with classical HLA-I, it is likely that hyperexpression of non-classical HLA-I is driven by the release of diffusible interferons by stressed β cells (potentially driven by viral infection) and exacerbated by release of cytokines from infiltrating immune cells. Summary Non-classical HLA-I proteins predominantly (but not exclusively) transduce negative signals to immune cells infiltrating at the site of injury/inflammation. We propose a model in which the islet endocrine cells, through expression of non-classical HLA-I are fighting back against the infiltrating immune cells. By inhibiting the activity and function on NK, B and select T cells, the non-classical HLA-I, proteins will reduce the non-specific bystander effects of inflammation, while at the same time still allowing the targeted destruction of β cells by specific islet-reactive CD8+ T cells.

Epithelial cell therapies have been at an impasse because of inefficient methods of transplantation to solid organs. Patch grafting strategies were established enabling transplantation of ≥10(7th) organoids/patch of porcine GFP+ biliary tree stem/progenitors into livers of wild type hosts. Grafts consisted of organoids embedded in soft (~100 Pa) hyaluronan hydrogels, both prepared in serum-free Kubota’s Medium; placed against target sites; covered with a silk backing impregnated with more rigid hyaluronan hydrogels (~700 Pa); and use of the backing to tether grafts with sutures or glue to target sites. Hyaluronan coatings (~200–300 Pa) onto the serosal surface of the graft served to minimize adhesions with neighboring organs. The organ’s clearance of hyaluronans enabled restoration of tissue-specific paracrine and systemic signaling, resulting in return of normal hepatic histology, with donor parenchymal cells uniformly integrated amidst host cells and that had differentiated to mature hepatocytes and cholangiocytes. Grafts containing donor mature hepatocytes, partnered with endothelia, and in the same graft biomaterials as for stem/progenitor organoids, did not engraft. Engraftment occurred if porcine liver-derived mesenchymal stem cells (MSCs) were co-transplanted with donor mature cells. RNA-seq analyses revealed that engraftment correlated with expression of matrix-metalloproteinases (MMPs), especially secreted isoforms that were found expressed strongly by organoids, less so by MSCs, and minimally, if at all, by adult cells. Engraftment with patch grafting strategies occurred without evidence of emboli or ectopic cell distribution. It was successful with stem/progenitor organoids or with cells with a source(s) of secreted MMP isoforms and offers significant potential for enabling cell therapies for solid organs.

The etiology of Type 1 Diabetes (T1D) remains elusive. Enzymatically isolated and cultured (EIC) islets cannot fully reflect the natural protein composition and disease process of in vivo islets, because of the stress from isolation procedures. In order to study islet protein composition in conditions close to the natural environment, we performed proteomic analysis of EIC islets, and laser capture microdissected (LCM) human islets and acinar tissue from fresh-frozen pancreas sections of three cadaveric donors. 1104 and 706 proteins were identified from 6 islets equivalents (IEQ) of LCM islets and acinar tissue, respectively. The proteomic profiles of LCM islets were reproducible within and among cadaveric donors. The endocrine hormones were only detected in LCM islets, whereas catalytic enzymes were significantly enriched in acinar tissue. Furthermore, high overlap (984 proteins) and similar function distribution were found between LCM and EIC islets proteomes, except that EIC islets had more acinar contaminants and stress-related signal transducer activity proteins. The comparison among LCM islets, LCM acinar tissue and EIC islets proteomes indicates that LCM combined with proteomic methods enables accurate and unbiased profiling of islet proteome from frozen pancreata. This paves the way for proteomic studies on human islets during the progression of T1D.The etiological agent triggering autoimmunity against beta cells in Type 1 diabetes (T1D) remains obscure. The in vitro models available (enzymatically isolated and cultured islets, EIC islets) do not accurately reflect what happens in vivo due to lack of the natural environment where islets exist and the preparation-induced changes in cell physiology. The importance of this study is that we investigated the feasibility of laser capture microdissection (LCM) for the isolation of intact islets from frozen cadaveric pancreatic tissue sections. We compared the protein profile of LCM islets (9 replicates from 3 cadaveric donors) with that of both LCM acinar tissues (6 replicates from the same 3 cadaveric donor as LCM islets) and EIC islets (at least 4 replicates for each sample with the same islets equivalents) by using proteomics techniques with advanced instrumentation, nanoLC-Q Exactive HF Orbitrap mass spectrometry (nano LC-MS/MS). The results demonstrate that the LCM method is reliable in isolating islets with an intact environment. LCM-based islet proteomics is a feasible approach to obtain good proteome coverage for assessing the pathology of T1D using cadaveric pancreatic samples, even from very small sample amounts. Future applications of this LCM-based proteomic method may help us understand the pathogenesis of T1D and identify potential biomarkers for T1D diagnosis at an early stage.

A large fraction of patients with diabetes mellitus require insulin treatment to control glucose metabolism; however, this treatment brings risks of hypoglycaemia and provides suboptimal metabolic control. Transplantation of stem cell-derived pancreatic islet cells could be an ideal solution, which is approaching clinical translation.

Pancreatic islet β cells synthesize the hormone insulin, which is fundamental for the control of glucose metabolism. β cells can be lost as the result of an autoimmune process, leading to type 1 diabetes (T1D), they can develop functional impairments in the context of insulin resistance (type 2 diabetes), or they can be impaired owing to genetic conditions compromising their development or function (monogenic diabetes). Cell-based therapies for beta-cell replacement are under investigation. Transplantation of cadaveric pancreas or pancreatic islets can correct diabetes, but the low numbers of organs available and the need for immunosuppression limit these strategies. β cells can be derived from embryonic stem cells, induced pluripotent stem cells, or adult stem/progenitor cells. Novel findings indicate that stem/progenitor cells exist in the adult human pancreas. Differentiation strategies are largely based on knowledge from embryology. Other regenerative strategies include reprogramming or the delivery of prodifferentiation signals. This chapter will also cover studies of mesenchymal stem cell (MSC) transplantation in diabetic patients. MSCs can modulate immunity and preserve or even stimulate the regeneration of β cells. MSCs had a good safety profile in initial clinical trials for T1D and are being tested as a therapeutic option for complications of diabetes mellitus.

Recurrence of autoimmunity and allograft rejection represent major challenges that impact the success of islet transplantation. Despite the remarkable improvements achieved in immunosuppression strategies after the publication of the Edmonton protocol, long-term data of intra-hepatic islet transplantation show a gradual decline in beta-cell function. Therefore, there is a growing interest in the investigation of novel, safe and effective anti-inflammatory and immunomodulatory strategies able to promote long-term islet graft survival and notable improvements in clinical outcomes of islet transplant recipients. Vitamin D has been shown to exert anti-inflammatory and immunomodulatory effects. Pre-clinical studies investigating the use of vitamin D and its analogs (alone or in combination with immunosuppressive agents and/or other anti-inflammatory agents, such as omega-3 polyunsaturated fatty acids) showed beneficial results in terms of islet graft survival and prevention of recurrence of autoimmunity/allograft rejection in animal models of syngeneic and allogeneic islet transplantation. Moreover, epidemiologic studies demonstrated that vitamin D deficiency is highly prevalent after solid organ transplantation (e.g., heart, liver or kidney transplantation). However, studies that critically assess the prevalence of vitamin D deficiency among islet transplant recipients have yet to be conducted. In addition, prospective studies aimed to address the safety and efficacy of vitamin D supplementation as an adjuvant immunomodulatory strategy in islet transplant recipients are lacking and are therefore awaited in the future.

Diabetes mellitus is caused by either loss of pancreatic islets β-cells (Type 1 Diabetes, T1D), insufficient insulin release in the islet β-cells coupled with insulin resistance in target tissues (Type 2 Diabetes, T2D), or impaired insulin release (genetic forms of diabetes and, possibly, T1D subtypes). The investigation of the islet proteome could elucidate facets of the pathogenesis of diabetes. Enzymatically isolated and cultured (EIC) islets are frequently used to investigate biochemical signaling pathways that could trigger β-cell changes and death in diabetes. However, they cannot fully reflect the natural protein composition and disease process of in vivo islets due to the stress from isolation procedures and in vitro culture. The laser capture microdissection method employs a high-energy laser source to separate the desired cells from the remaining tissue section in an environment which is well conserved and close to the natural condition. Here, we describe a label-free proteomic workflow of laser capture microdissected (LCM) human islets from fresh-frozen pancreas sections of cadaveric donors to obtain an accurate and unbiased profile of the pancreatic islet proteome. The workflow includes preparation of frozen tissue section, staining and dehydration, LCM islets collection, islet protein digestion, label free Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS), database search, and statistical analysis.

Islet transplantation is an effective cell therapy for type 1 diabetes (T1D) but its clinical application is limited due to shortage of donors. After a decade-long period of exploration of potential alternative cell sources, the field has only recently zeroed in on two of them as the most likely to replace islets. These are pluripotent stem cells (PSCs) (through directed differentiation) and pancreatic non-endocrine cells (through directed differentiation or reprogramming). Here we review progress in both areas, including the initiation of Phase I/II clinical trials using human embryonic stem cell (hESc)-derived progenitors, advances in hESc differentiation in vitro, novel insights on the developmental plasticity of the pancreas, and groundbreaking new approaches to induce β cell conversion from the non-endocrine compartment without genetic manipulation.

Stem/progenitors for liver, biliary tree, and pancreas exist at early stages of development in the definitive ventral endoderm forming the foregut. In humans, they persist postnatally as part of a network, with evidence supporting their contributions to hepatic and pancreatic organogenesis throughout life. Multiple stem cell niches persist in specific anatomical locations within the human biliary tree and pancreatic ducts. In liver and pancreas, replication of mature parenchymal cells ensures the physiological turnover and the restoration of parenchyma after minor injuries. Although actively debated, multiple observations indicate that stem/progenitor cells contribute to repair pervasive, chronic injuries. The most primitive of the stem/progenitor cells, biliary tree stem cells, are found in peribiliary glands within extrahepatic and large intrahepatic bile ducts. Biliary tree stem cells are comprised of multiple subpopulations with traits suggestive of maturational lineage stages and yet capable of self-replication and multipotent differentiation, being able to differentiate to mature liver cells (hepatocytes, cholangiocytes) and mature pancreatic cells (including functional islet endocrine cells). Hepatic stem cells are located within canals of Hering and bile ductules and are capable of differentiating to hepatocyte and cholangiocyte lineages. The existence, phenotype, and anatomical location of stem/progenitors in the adult pancreas are actively debated. Ongoing studies suggest that pancreatic stem cells reside within the biliary tree, primarily the hepatopancreatic common duct, and are rare in the pancreas proper. Pancreatic ducts and pancreatic duct glands harbor committed pancreatic progenitors. Conclusion: The hepatic, biliary, and pancreatic network of stem/progenitor cell niches should be considered as a framework for understanding liver and pancreatic regeneration after extensive or chronic injuries and for the study of human chronic diseases affecting these organs. (Hepatology 2016;64:277-286)

Introduction: Bone morphogenetic protein 7 (BMP-7), a protein with BMP-activating and TGF-β inactivating properties, induces the proliferation of a unique population of progenitor-like cells characterized by the expression of PDX1 and the BMP receptor activin-like kinase 3 (ALK3/BMPR1A). These cells can be sorted using ALK3 and the purinergic receptor P2Y1 (P2RY1) as a novel surrogate surface marker for PDX1. Sorted P2RY1+/ALK3bright+ cells form BMP-7 expandable colonies. Upon BMP-7 withdrawal, they differentiate into cells of all three lineages (endocrine, acinar and ductal) of the adult pancreas. PDX1+/ALK3+ cells absent from islets are represented in the major pancreatic ducts and pancreatic duct glands. Preliminary evidence indicates that these cells are also present in the murine pancreas. We hypothesized that islet β-cell regeneration could be studied in real time using live murine pancreatic slices transduced with a loxP-dsRed-loxP-EGFP reporter + insulin promoter-Cre adenovirus. If new β-cells arise from preexisting insulin-expressing-cells they would remain green. However, if neogenesis occurs from non-β-cells, there is a window of time during which the degrading red and the new green protein co-localize in the cell. Allowing us to discriminate between neogenesis and β-cell proliferation. Methods: Low melting point (LMP) agarose-embedded, vibratome-sectioned live pancreatic slices were generated from CD-1 mice. Transduction with a loxP-dsRed-loxP-EGFP reporter + insulin promoter-Cre adenovirus was done in slices cultured atop optically clear membranes. Slices were treated for 4 days with an ALK3 agonist (THR-123) or saline at the same time of the co-transduction. Bright field and fluorescence images of them were taken every 24h for 7 days. Conclusions: This is the first report on the use of live pancreatic slices as a novel tool for the study of pancreatic regeneration. Our preliminary results suggest that there are quantifiable β-cell neogenic events in response to BMP-7-like agents. Disclosure F. Qadir: None. J. Weitz: None. S. Alvarez-Cubela: None. D. Klein: None. G. Lanzoni: None. C.A. Garcia-Santana: Employee; Self; Ophysio Incorporated. A. Montalvo: None. C. Ricordi: None. L. Inverardi: None. A. Caicedo: None. R. Pastori: None. J. Domínguez-Bendala: Stock/Shareholder; Self; Ophysio.

The exocrine pancreas can give rise to endocrine insulin-producing cells upon ectopic expression of key transcription factors. However, the need for genetic manipulation remains a translational hurdle for diabetes therapy. Here we report the conversion of adult human nonendocrine pancreatic tissue into endocrine cell types by exposure to bone morphogenetic protein 7. The use of this U.S. Food and Drug Administration–approved agent, without any genetic manipulation, results in the neogenesis of clusters that exhibit high insulin content and glucose responsiveness both in vitro and in vivo. In vitro lineage tracing confirmed that BMP-7–induced insulin-expressing cells arise mainly from extrainsular PDX-1+, carbonic anhydrase II− (mature ductal), elastase 3a (acinar)−, and insulin− subpopulations. The nongenetic conversion of human pancreatic exocrine cells to endocrine cells is novel and represents a safer and simpler alternative to genetic reprogramming.

The possible use of cell therapies for neurological lesions and disorders is regarded as a very promising strategy. However, many issues related to cell type, tissue donor, expected biological action etc., are still open. In this study human mesenchymal stem cells derived from different fetal and adult tissues were examined in order to explore growth and neurotrophic factor synthesis and biological action, also considering the individual variability of the donors. Cells were derived from different human tissues and characterized according to the guidelines of the International Society for Cellular Therapy. Growth and neurotrophic factor synthesis was evaluated by real time PCR, biological assays and ELISA. It was found that human mesenchymal stem cells produce vascular endothelial-, nerve-growth factor (VEGF, NGF), brain-derived-, ciliary- and glial-derived neurotrophic factors (BDNF, CDGF, GDNF), which are neuroprotective molecules, but the source and the donor influence the synthesis rate. Accordingly, it is suggested that the source and the individual variability are key issues to be considered in the perspective of the clinical use of mesenchymal stem cells in neurological disorders.

M. Paradisi, M. Fernandez, G. Del Vecchio, G. Lizzo, G. Marucci, M. Giulioni, E. Pozzati, T. Antonelli, G. Lanzoni, G. P. Bagnara, L. Giardino and L. Calza (2010) Neuropathology and Applied Neurobiology36, 535–550 Ex vivo study of dentate gyrus neurogenesis in human pharmacoresistant temporal lobe epilepsy Aims: Neurogenesis in adult humans occurs in at least two areas of the brain, the subventricular zone of the telencephalon and the subgranular layer of the dentate gyrus in the hippocampal formation. We studied dentate gyrus subgranular layer neurogenesis in patients subjected to tailored antero-mesial temporal resection including amygdalohippocampectomy due to pharmacoresistant temporal lobe epilepsy (TLE) using the in vitro neurosphere assay. Methods: Sixteen patients were enrolled in the study; mesial temporal sclerosis (MTS) was present in eight patients. Neurogenesis was investigated by ex vivo neurosphere expansion in the presence of mitogens (epidermal growth factor + basic fibroblast growth factor) and spontaneous differentiation after mitogen withdrawal. Growth factor synthesis was investigated by qRT-PCR in neurospheres. Results: We demonstrate that in vitro proliferation of cells derived from dentate gyrus of TLE patients is dependent on disease duration. Moreover, the presence of MTS impairs proliferation. As long as in vitro proliferation occurs, neurogenesis is maintained, and cells expressing a mature neurone phenotype (TuJ1, MAP2, GAD) are spontaneously formed after mitogen withdrawal. Finally, formed neurospheres express mRNAs encoding for growth (vascular endothelial growth factor) as well as neurotrophic factors (brain-derived neurotrophic factor, ciliary neurotrophic factor, glial-derived neurotrophic factor, nerve growth factor). Conclusion: We demonstrated that residual neurogenesis in the subgranular layer of the dentate gyrus in TLE is dependent on diseases duration and absent in MTS.

Among the many cell types that may prove useful to regenerative medicine, mounting evidence suggests that human term placenta-derived cells will join the list of significant contributors. In making new cell therapy-based strategies a clinical reality, it is fundamental that no a priori claims are made regarding which cell source is preferable for a particular therapeutic application. Rather, ongoing comparisons of the potentiality and characteristics of cells from different sources should be made to promote constant improvement in cell therapies, and such comparisons will likely show that individually tailored cells can address disease-specific clinical needs. The principle underlying such an approach is resistance to the notion that comprehensive characterization of any cell type has been achieved, neither in terms of phenotype nor risks-to-benefits ratio. Tailoring cell therapy approaches to specific conditions also requires an understanding of basic disease mechanisms and close collaboration between translational researchers and clinicians, to identify current needs and shortcomings in existing treatments. To this end, the international workshop entitled Placenta-derived stem cells for treatment of inflammatory diseases: moving toward clinical application was held in Brescia, Italy, in March 2009, and aimed to harness an understanding of basic inflammatory mechanisms inherent in human diseases with updated findings regarding biological and therapeutic properties of human placenta-derived cells, with particular emphasis on their potential for treating inflammatory diseases. Finally, steps required to allow their future clinical application according to regulatory aspects including good manufacturing practice (GMP) were also considered. In September 2009, the International Placenta Stem Cell Society (IPLASS) was founded to help strengthen the research network in this field.

Background aims. The presence of ectopic tissues in the pathologic artery wall raises the issue of whether multipotent stem cells may reside in the vasculature itself. Recently mesenchymal stromal cells (MSC) have been isolated from different human vascular segments (VW MSC), belying the previous view that the vessel wall is a relatively quiescent tissue. Methods. Resident multipotent cells were recovered from fresh arterial segments (aortic arches, thoracic and femoral arteries) collected in a tissue-banking facility and used to establish an in situ and in vitr o study of the stemness features and multipotency of these multidistrict MSC populations. Results. Notch-1 � , Stro-1 � , Sca-1 � and Oct-4 � cells were distributed along an arterial wall vasculogenic niche. Multidistrict VW MSC homogeneously expressed markers of stemness (Stro-1, Notch-1 and Oct-4) and MSC lineages (CD44, CD90, CD105, CD73, CD29 and CD166) whilst they were negative for hematopoietic and endothe- lial markers (CD34, CD45, CD31 and vWF). Each VW MSC population had characteristics of stem cells, i.e. a high effl ux capability for Hoechst 33342 dye and the ability to form spheroids when grown in suspension and generate colonies when seeded at low density. Again, VW MSC cultured in induction media exhibited adipogenic, chondrogenic and leiomyogenic potential but less propensity to osteogenic differentiation, as documented by histochemical, immunohistochemical, molecular and electron microscopy analysis. Conclusions. Overall, these fi ndings may enlighten the physiopathologic mechanisms of vascular wall diseases as well as having potential implications for cellular, genetic and tissue engineering approaches to treating vascular pathologies when these are unresponsive to medical and surgical therapies.

New cell sorting methodologies, which are simple, fast, non-invasive, and able to isolate homogeneous cell populations, are needed for applications ranging from gene expression analysis to cell-based therapy. In particular, in the forefront of stem cell isolation, progenitor cells have to be separated under mild experimental conditions from complex heterogeneous mixtures prepared from human tissues. Most of the methodologies now employed make use of immunological markers. However, it is widely acknowledged that specific markers for pluripotent stem cells are not as yet available, and cell labelling may interfere with the differentiation process. This work presents for the first time gravitational field-flow fractionation (GrFFF), as a tool for tag-less, direct selection of human hematopoietic stem and progenitor cells from cell samples obtained by peripheral blood aphaeresis. These cells are responsible to repopulate the hemopoietic system and they are used in transplantation therapies. Blood aphaeresis sample were injected into a GrFFF system and collected fractions were characterized by flow cytometry for CD34 and CD45 expression, and then tested for viability and multi-differentiation potential. The developed GrFFF method allowed obtaining high enrichment levels of viable, multi-potent hematopoietic stem cells in specific fraction and it showed to fulfil major requirements of analytical performance, such as selectivity and reproducibility of the fractionation process and high sample recovery.

Background: The interest in stem cell (SC) isolation from easily accessible clinical specimens is booming. The lack of homogeneity in pluri/multipotent SC preparation blurs standardization, which however is recommended for successful applications. Multipotent mesenchymal SCs (MSCs) in fact express a broad panel of surface antigens, which limit the possibility of sorting homogeneous preparations by using an immunotag-based method. Methods: We present a tag-less, flow-assisted method to purify, distinguish, and sort pluri/multipotent SCs obtained from clinical specimens, based on differences in the biophysical properties that cells acquire when in suspension under fluidic conditions. A suspension of cells in a transport fluid is injected into a ribbon-like capillary device by continuous flow. In a relatively short time (about 30 min), sorted cells are collected. Results: We obtained baseline separation between MSCs and epithelial cells, which are important contaminants of isolated MSCs. The extent of separation is evaluated by flow cytometry through detection of a specific epithelial antigen. MSCs from various human sources also prove to have different, characteristic, highly-reproducible fractionation profiles. Finally, we evaluated the dissimilar differentiation potential among cell fractions obtained from sorting a single MSC source. After differentiation induction, a fraction displayed a differentiation yield close to 100%, whereas unfractionated cells contained only 40% of responding cells. Conclusions: The results demonstrate that the method presented is able to obtain selected and well-characterized living MSCs with an increased differentiation yield. Its reduced cost, full biocompatibility, and scale-up potential could make this method an effective procedure for stem cell selection. © 2009 Clinical Cytometry Society

Bone marrow (BM)- and adipose tissue (AT)-derived mesenchymal stromal cells (MSC) are currently under evaluation in phase III clinical trials for inflammatory bowel disease and other intestinal disease manifestations. The therapeutic efficacy of these treatments may derive from a combination of the differentiation, trophic and immunomodulatory abilities of the transplanted cells. We investigated intestinal tissues as sources of MSC: such cells may support tissue-specific functions and hold advantages for engraftment and contribution in the gastrointestinal environment.Intestinal specimens were collected, and the mucosa and submucosa mechanically separated and enzymatically digested. Mesenchymal stromal populations were isolated, expanded and characterized under conditions commonly used for MSC. The differentiation potential, trophic effect and immunomodulatory ability were investigated. Results We successfully isolated and extensively expanded populations showing the typical MSC profile: CD29+, CD44+, CD73+, CD105+ and CD166+, and CD14(-), CD34(-) and CD45(-). Intestinal mucosal (IM) MSC were also CD117+, while submucosal cultures (ISM MSC) showed CD34+ subsets. The cells differentiated toward osteogenic, adipogenic and angiogenic commitments. Intestinal-derived MSC were able to induce differentiation and organization of intestinal epithelial cells (Caco-2) in three-dimensional collagen cultures. Immunomodulatory activity was evidenced in co-cultures with normal heterologous phytohemagglutinin-stimulated peripheral blood mononuclear cells. Conclusions Multipotent MSC can be isolated from intestinal mucosal and submucosal tissues. IM MSC and ISM MSC are able to perform trophic and immunomodulatory functions. These findings could open a pathway for novel approaches to intestinal disease treatment.

The quest for therapies that can normalize blood glucose control and provide independence from exogenous insulin could impact the life of millions of patients with type 1 diabetes (T1D) and a significant subset of patients with type 2 diabetes (T2D) with a functional deficiency in insulin production. Islet transplantation could be considered the first clinically successful cell therapy for T1D, but its widespread application is still hampered by the need for immunosuppression and the scarcity of organs available for processing and transplantation. The existence of these roadblocks has fostered the development of alternative approaches aimed at identifying high-yield sources of insulin-producing cells. Here we will discuss the state of the art in regenerative therapies for pancreatic islets, from stem cells to reprogramming. An outlook of the pancreatic development blueprint will help us in understanding key steps of stem cell differentiation, guiding us in the design of clinically translatable strategies. Major hurdles remain to be overcome for these approaches to find their way to the clinic: of these, we will specifically emphasize yield, safety, and immunological challenges.

Regenerative medicine is transitioning into clinical programs using stem/progenitor cell therapies for repair of damaged organs. We summarize those for liver and pancreas, organs that share endodermal stem cell populations, biliary tree stem cells (hBTSCs), located in peribiliary glands. They are precursors to hepatic stem/progenitors in canals of Hering and to committed progenitors in pancreatic duct glands. They give rise to maturational lineages along a radial axis within bile duct walls and a proximal-to-distal axis starting at the duodenum and ending with mature cells in the liver or pancreas. Clinical trials have been ongoing for years assessing effects of determined stem cells (fetal-liver-derived hepatic stem/progenitors) transplanted into the hepatic artery of patients with various liver diseases. Immunosuppression was not required. Control subjects, those given standard of care for a given condition, all died within a year or deteriorated in their liver functions. Subjects transplanted with 100-150 million hepatic stem/progenitor cells had improved liver functions and survival extending for several years. Full evaluations of safety and efficacy of transplants are still in progress. Determined stem cell therapies for diabetes using hBTSCs remain to be explored but are likely to occur following ongoing preclinical studies. In addition, mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) are being used for patients with chronic liver conditions or with diabetes. MSCs have demonstrated significant effects through paracrine signaling of trophic and immunomodulatory factors, and there is limited evidence for inefficient lineage restriction into mature parenchymal or islet cells. HSCs' effects are primarily via modulation of immune mechanisms.

Peribiliary glands (PBGs) in bile duct walls, and pancreatic duct glands (PDGs) associated with pancreatic ducts, in humans of all ages, contain a continuous, ramifying network of cells in overlapping maturational lineages. We show that proximal (PBGs)-to-distal (PDGs) maturational lineages start near the duodenum with cells expressing markers of pluripotency (NANOG, OCT4, and SOX2), proliferation (Ki67), self-replication (SALL4), and early hepato-pancreatic commitment (SOX9, SOX17, PDX1, and LGR5), transitioning to PDG cells with no expression of pluripotency or self-replication markers, maintenance of pancreatic genes (PDX1), and expression of markers of pancreatic endocrine maturation (NGN3, MUC6, and insulin). Radial-axis lineages start in PBGs near the ducts' fibromuscular layers with stem cells and end at the ducts' lumens with cells devoid of stem cell traits and positive for pancreatic endocrine genes. Biliary tree-derived cells behaved as stem cells in culture under expansion conditions, culture plastic and serum-free Kubota's Medium, proliferating for months as undifferentiated cells, whereas pancreas-derived cells underwent only approximately 8–10 divisions, then partially differentiated towards an islet fate. Biliary tree-derived cells proved precursors of pancreas' committed progenitors. Both could be driven by three-dimensional conditions, islet-derived matrix components and a serum-free, hormonally defined medium for an islet fate (HDM-P), to form spheroids with ultrastructural, electrophysiological and functional characteristics of neoislets, including glucose regulatability. Implantation of these neoislets into epididymal fat pads of immunocompromised mice, chemically rendered diabetic, resulted in secretion of human C-peptide, regulatable by glucose, and able to alleviate hyperglycemia in hosts. The biliary tree-derived stem cells and their connections to pancreatic committed progenitors constitute a biological framework for life-long pancreatic organogenesis.

Determined stem cells for liver and pancreas are present in stem cell niches, peribiliary glands (PBGs), throughout the biliary tree. PBGs are connected to intrahepatic stem cell niches, canals of Hering, and niches of committed progenitors, pancreatic duct glands. The phenotypic traits in the most primitive populations comprise both liver and pancreatic markers (transcription factors, pluripotency genes, endodermal genes), and their highest numbers are in large intrahepatic bile ducts and the hepato-pancreatic common duct. Their descendants have phenotypic traits implicating maturational lineages along a radial axis within bile duct walls and a proximal-to-distal axis from duodenum to mature cells near or in the liver or pancreas. The stem cells and lineages constitute a biological framework for hepatic and pancreatic organogenesis throughout life.

Mesenchymal stromal cells (also often referred to as mesenchymal stem cells, MSCs) hold promise as a powerful tool in the treatment of human diseases. Because of their potent immunomodulatory properties, they are likely to impact in a positive fashion diseases in which inflammation and/or autoimmunity play a key role. Furthermore, they have been shown to possess plasticity as precursors of cells of various types. Their differentiation potential could span cell differentiation products that do not normally derive from the mesoderm, including cells of endodermal origin. These two remarkable features make them potentially ideal candidates for regenerative approaches. This chapter will briefly discuss the current state of the art in the emerging field of their use for autoimmune type 1 diabetes.

BACKGROUNDAllogeneic human islet transplantation is an effective therapy for the treatment of patients with Type 1 Diabetes (T1D). The low number of islet transplants performed worldwide and the different transplantation protocols used limit the identification of the most effective therapeutic options to improve the efficacy of this approach.METHODSWe present a retrospective analysis on the data collected from 44 patients with T1D who underwent islet transplantation at our institute between 2000 and 2007. Several variables were included: recipient demographics and immunological characteristics, donor and transplant characteristics, induction protocols, and additional medical treatment received. Immunosuppression was induced with anti-CD25 (Daclizumab), alone or in association with anti-tumor necrosis factor alpha (TNF-α) treatments (Etanercept or Infliximab), or with anti-CD52 (Alemtuzumab) in association with anti-TNF-α treatments (Etanercept or Infliximab). Subsets of patients were treated with Filgrastim for moderate/severe neutropenia and/or Exenatide for post prandial hyperglycemia.RESULTSThe analysis performed indicates a negative association between graft survival (c-peptide level ≥ 0.3 ng/ml) and islet infusion volume, with the caveat that, the progressive reduction of infusion volumes over the years has been paralleled by improved immunosuppressive protocols. A positive association is instead suggested between graft survival and administration of Exenatide and Filgrastim, alone or in combination.CONCLUSIONThis retrospective analysis may be of assistance to further improve long-term outcomes of protocols for transplant of islets and other organs.

Mesenchymal stem cells (MSCs) have already made their mark in the young field of regenerative medicine. Easily derived from many adult tissues, their therapeutic worth has already been validated for a number of conditions. Unlike embryonic stem cells, neither their procurement nor their use is deemed controversial. Here we review the potential use of MSCs for the treatment of type 1 diabetes mellitus, a devastating chronic disease in which the insulin-producing cells of the pancreas (the β-cells) are the target of an autoimmune process. It has been hypothesized that stem cell-derived β-cells may be used to replenish the islet mass in diabetic patients, making islet transplantation (a form of cell therapy that has already proven effective at clinically restoring normoglycemia) available to millions of prospective patients. Here we review the most current advances in the design and application of protocols for the differentiation of transplantable β-cells, with a special emphasis in analyzing MSC potency according to their tissue of origin. Although no single method appears to be ripe enough for clinical trials yet, recent progress in reprogramming (a biotechnological breakthrough that relativizes the thus far insurmountable barriers between embryonal germ layers) bodes well for the rise of MSCs as a potential weapon of choice to develop personalized therapies for type 1 diabetes.