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The 3d organization of the genome - in particular, which two regions of DNA are in contact with each other - plays a role in regulating gene expression. Several factors influence genome 3d organization. Nucleosomes (where ~ 100 basepairs of DNA wrap around histone proteins) also bend, twist and compactify chromosomal DNA, altering its polymer mechanics. How much does the positioning of nucleosomes between gene loci influence contacts between those gene loci? And, to what extent is polymer mechanics responsible for this? To address this question, we combine a stochastic polymer mechanics model of chromosomal DNA including twists and wrapping induced by nucleosomes with two data-driven pipelines. The first estimates nucleosome positioning from ATACseq data in regions of high accessibility. Most of the genome is low-accessibility, so we combine this with a novel image analysis method that estimates the distribution of nucleosome spacing from electron microscopy data. There are no free parameters in the biophysical model. We apply this method to IL6, IL15, CXCL9, and CXCL10, inflammatory marker genes in macrophages, before and after immune stimulation, and compare the predictions with contacts measured by conformation capture experiments (4C-seq). We find that within a 500 kilo-basepairs genomic region, polymer mechanics with nucleosomes can explain 71% of close contacts. These results suggest that, while genome contacts on 100kbp-scales are multifactorial, they may be amenable to mechanistic, physical explanation. Our work also highlights the role of nucleosomes, not just at the loci of interest, but between them, and not just the total number of nucleosomes, but their specific placement. The method generalizes to other genes, and can be used to address whether a contact is under active regulation by the cell (e.g., a macrophage during inflammatory stimulation). Importantly, our findings suggest that gene function may have evolved through selective pressures that co-opted contact-mediated regulatory mechanisms reliant largely on polymer mechanics.

We investigate how matrix stiffness regulates chromatin reorganization and cell reprogramming and find that matrix stiffness acts as a biphasic regulator of epigenetic state and fibroblast-to-neuron conversion efficiency, maximized at an intermediate stiffness of 20 kPa. ATAC sequencing analysis shows the same trend of chromatin accessibility to neuronal genes at these stiffness levels. Concurrently, we observe peak levels of histone acetylation and histone acetyltransferase (HAT) activity in the nucleus on 20 kPa matrices, and inhibiting HAT activity abolishes matrix stiffness effects. G-actin and cofilin, the cotransporters shuttling HAT into the nucleus, rises with decreasing matrix stiffness; however, reduced importin-9 on soft matrices limits nuclear transport. These two factors result in a biphasic regulation of HAT transport into nucleus, which is directly demonstrated on matrices with dynamically tunable stiffness. Our findings unravel a mechanism of the mechano-epigenetic regulation that is valuable for cell engineering in disease modeling and regenerative medicine applications.

The role of transcription factors and biomolecules in cell type conversion has been widely studied. Yet, it remains unclear whether and how intracellular mechanotransduction through focal adhesions (FAs) and the cytoskeleton regulates the epigenetic state and cell reprogramming. Here, it is shown that cytoskeletal structures and the mechanical properties of cells are modulated during the early phase of induced neuronal (iN) reprogramming, with an increase in actin cytoskeleton assembly induced by Ascl1 transgene. The reduction of actin cytoskeletal tension or cell adhesion at the early phase of reprogramming suppresses the expression of mesenchymal genes, promotes a more open chromatin structure, and significantly enhances the efficiency of iN conversion. Specifically, reduction of intracellular tension or cell adhesion not only modulates global epigenetic marks, but also decreases DNA methylation and heterochromatin marks and increases euchromatin marks at the promoter of neuronal genes, thus enhancing the accessibility for gene activation. Finally, micro- and nano-topographic surfaces that reduce cell adhesions enhance iN reprogramming. These novel findings suggest that the actin cytoskeleton and FAs play an important role in epigenetic regulation for cell fate determination, which may lead to novel engineering approaches for cell reprogramming., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

DNA methylation aberrancies are found in autosomal dominant polycystic kidney disease (ADPKD), which suggests the methylome to be a promising therapeutic target. However, the impact of combining DNA methylation inhibitors (DNMTi) and ADPKD drugs in treating ADPKD and on disease-associated methylation patterns has not been fully explored. To test this, ADPKD drugs, metformin and tolvaptan (MT), were delivered in combination with DNMTi 5-aza-2'-deoxycytidine (Aza) to 2D or 3D cystic Pkd1 heterozygous renal epithelial cells (PKD1-Het cells) as free drugs or within nanoparticles to enable direct delivery for future in vivo applications. We found Aza synergizes with MT to reduce cell viability and cystic growth. Reduced representation bisulfite sequencing (RRBS) was performed across four groups: PBS, Free-Aza (Aza), Free-Aza+MT (F-MTAza), and Nanoparticle-Aza+MT (NP-MTAza). Global methylation patterns showed that while Aza alone induces a unimodal intermediate methylation landscape, Aza+MT recovers the bimodality reminiscent of somatic methylomes. Importantly, site-specific methylation changes associated with F-MTAza and NP-MTAza were largely conserved including hypomethylation at ADPKD-associated genes. Notably, we report hypomethylation of cancer-associated genes implicated in ADPKD pathogenesis as well as new target genes that may provide additional therapeutic effects. Overall, this study motivates future work to further elucidate the regulatory mechanisms of observed drug synergy and apply these combination therapies in vivo ., Competing Interests: The authors have no conflicts to disclose., (© 2023 Author(s).)

Innate immune cells are responsible for eliminating foreign infectious agents and cellular debris, and their ability to perceive, respond to, and integrate biochemical and mechanical cues from their microenvironment eventually determines their behavior. In response to tissue injury, pathogen invasion, or a biomaterial implant, immune cells activate many pathways to initiate inflammation in the tissue. In addition to common inflammatory pathways, studies have demonstrated the role of the mechanosensitive proteins and transcriptional coactivators YAP and TAZ (YAP/TAZ) in inflammation and immunity. We review our knowledge of YAP/TAZ in controlling inflammation and immunity in innate immune cells. Furthermore, we discuss the roles of YAP/TAZ in inflammatory diseases, wound healing, and tissue regeneration and how they integrate mechanical cues with biochemical signaling during disease progression. Last, we comment on possible approaches that can be exploited to harness the therapeutic potential of YAP/TAZ in inflammatory diseases.

Esophageal pathologies such as atresia and benign strictures often require surgical reconstruction with autologous tissues to restore organ continuity. Complications such as donor site morbidity and limited tissue availability have spurred the development of acellular grafts for esophageal tissue replacement. Acellular biomaterials for esophageal repair rely on the activation of intrinsic regenerative mechanisms to mediate de novo tissue formation at implantation sites. Previous research has identified signaling cascades involved in neoepithelial formation in a rat model of onlay esophagoplasty with acellular silk fibroin grafts, including phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt) signaling. However, it is currently unknown how these mechanisms are governed by DNA methylation (DNAme) during esophageal wound healing processes. Reduced-representation bisulfite sequencing is performed to characterize temporal DNAme dynamics in host and regenerated tissues up to 1 week postimplantation. Overall, global hypermethylation is observed at postreconstruction timepoints and an inverse correlation between promoter DNAme and the expression levels of differentially expressed proteins during regeneration. Site-specific hypomethylation targets genes associated with immune activation, while hypermethylation occurs within gene bodies encoding PI3K-Akt signaling components during the tissue remodeling period. The data provide insight into the epigenetic mechanisms during esophageal regeneration following surgical repair with acellular grafts., (© 2023 Wiley-VCH GmbH.)

DNA methylation occurs predominantly on cytosine-phosphate-guanine (CpG) dinucleotides in the mammalian genome, and the methylation landscape is maintained over mitotic cell division. It has been posited that coupling of maintenance methylation activity among neighbouring CpGs is critical to stability over cellular generations; however, the mechanism is unclear. We used mathematical models and stochastic simulation to analyse data from experiments that probe genome-wide methylation of nascent DNA post-replication in cells. We find that DNA methylation maintenance rates on individual CpGs are locally correlated, and the degree of this correlation varies by genomic regional context. By using theory of protein diffusion along DNA, we show that exponential decay of methylation rate correlation with genomic distance is consistent with enzyme processivity. Our results provide quantitative evidence of genome-wide methyltransferase processivity in vivo . We further developed a method to disentangle different mechanistic sources of kinetic correlations. From the experimental data, we estimate that an individual methyltransferase methylates neighbour CpGs processively if they are 36 basepairs apart, on average. But other mechanisms of coupling dominate for longer inter-CpG distances. Our study demonstrates that quantitative insights into enzymatic mechanisms can be obtained from replication-associated, cell-based genome-wide measurements, by combining data-driven statistical analyses with hypothesis-driven mathematical modelling.

Macrophages are innate immune cells that help wounds heal. Here, we study the potential immunomodulatory effects of negative-pressure wound therapy (NPWT) materials on the macrophage inflammatory response. We compared the effects of two materials, Granufoam™ (GF) and Veraflo Cleanse™ (VC), on macrophage function in vitro. We find that both materials cause reduced expression of inflammatory genes, such as TNF and IL1B, in human macrophages stimulated with bacterial lipopolysaccharide (LPS) and interferon-gamma (IFNγ). Relative to adherent glass control surfaces, VC discourages macrophage adhesion and spreading, and may potentially sequester LPS/IFNγ and cytokines that the cells produce. GF, on the other hand, was less suppressive of inflammation, supported macrophage adhesion and spreading better than VC, and sequestered lesser quantities of LPS/IFNγ in comparison to VC. The control dressing material cotton gauze (CT) was also immunosuppressive, capable of TNF-α retention and LPS/IFNγ sequestration. Our findings suggest that NPWT material interactions with cells, as well as soluble factors including cytokines and LPS, can modulate the immune response, independent of vacuum application. We have also established methodological strategies for studying NPWT materials and reveal the potential utility of cell-based in vitro studies for elucidating biological effects of NPWT materials.

DNA methylation is a well-characterized epigenetic modification involved in numerous molecular and cellular functions. Methylation patterns have also been associated with aging mechanisms. However, how DNA methylation patterns change within key brain regions involved in memory formation in an age- and sex-specific manner remains unclear. Here, we performed reduced representation bisulfite sequencing (RRBS) from mouse dorsal hippocampus - which is necessary for the formation and consolidation of specific types of memories - in young and aging mice of both sexes. Overall, our findings demonstrate that methylation levels within the dorsal hippocampus are divergent between sexes during aging in genomic features correlating to mRNA functionality, transcription factor binding sites, and gene regulatory elements. These results define age-related changes in the methylome across genomic features and build a foundation for investigating potential target genes regulated by DNA methylation in an age- and sex-specific manner., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Macrophages are mechanosensitive cells that can exquisitely fine-tune their function in response to their microenvironment. While macrophage polarization results in concomitant changes in cell morphology and epigenetic reprogramming, how biophysically-induced signaling cascades contribute to gene regulatory programs that drive polarization remains unknown. We reveal a cytoskeleton-dependent Src-H3 acetylation (H3Ac) axis responsible for inflammation-associated histone hyperacetylation. Inflammatory stimuli caused increases in traction forces, Src activity and H3Ac marks in macrophages, accompanied by reduced cell elongation and motility. These effects were curtailed following disruption of H3Ac-signaling through either micropattern-induced cell elongation or inhibition of H3Ac readers (BRD proteins) directly. Src activation relieves the suppression of p300 histone acetyltransferase (HAT) activity by PKCδ. Furthermore, while inhibition of Src reduced p300 HAT activity and H3Ac marks globally, local H3Ac levels within the Src promoter were increased, suggesting H3Ac regulates Src levels through feedback. Together, our study reveals an adhesome-to-epigenome regulatory nexus underlying macrophage mechanosensation, where Src modulates H3Ac-associated epigenetic signaling as a means of tuning inflammatory gene activity and macrophage fate decisions in response to microenvironmental cues., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Mutations in LMNA, encoding lamin A/C, lead to a variety of diseases known as laminopathies including dilated cardiomyopathy (DCM) and skeletal abnormalities. Though previous studies have investigated the dysregulation of gene expression in cells from patients with DCM, the role of epigenetic (gene regulatory) mechanisms, such as DNA methylation, has not been thoroughly investigated. Furthermore, the impact of family-specific LMNA mutations on DNA methylation is unknown. Here, we performed reduced representation bisulfite sequencing on ten pairs of fibroblasts and their induced pluripotent stem cell (iPSC) derivatives from two families with DCM due to distinct LMNA mutations, one of which also induces brachydactyly., Results: Family-specific differentially methylated regions (DMRs) were identified by comparing the DNA methylation landscape of patient and control samples. Fibroblast DMRs were found to enrich for distal regulatory features and transcriptionally repressed chromatin and to associate with genes related to phenotypes found in tissues affected by laminopathies. These DMRs, in combination with transcriptome-wide expression data and lamina-associated domain (LAD) organization, revealed the presence of inter-family epimutation hotspots near differentially expressed genes, most of which were located outside LADs redistributed in LMNA-related DCM. Comparison of DMRs found in fibroblasts and iPSCs identified regions where epimutations were persistent across both cell types. Finally, a network of aberrantly methylated disease-associated genes revealed a potential molecular link between pathways involved in bone and heart development., Conclusions: Our results identified both shared and mutation-specific laminopathy epimutation landscapes that were consistent with lamin A/C mutation-mediated epigenetic aberrancies that arose in somatic and early developmental cell stages., (© 2021. The Author(s).)

Aging is associated with decreased antigen-specific immunity and increased chronic inflammation. While DNA-sensing pathways might be involved, the molecular factors underlying these age-related aberrancies in immune signaling are unclear. Here, we consider the potential role of aging-induced hypomethylated DNA as a putative stimulant of age-associated inflammation., Competing Interests: Declaration of interests No interests are declared., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Macrophages are innate immune cells that adhere to the extracellular matrix within tissues. However, how matrix properties regulate their function remains poorly understood. Here, we report that the adhesive microenvironment tunes the macrophage inflammatory response through the transcriptional coactivator YAP. We find that adhesion to soft hydrogels reduces inflammation when compared to adhesion on stiff materials and is associated with reduced YAP expression and nuclear localization. Substrate stiffness and cytoskeletal polymerization, but not adhesive confinement nor contractility, regulate YAP localization. Furthermore, depletion of YAP inhibits macrophage inflammation, whereas overexpression of active YAP increases inflammation. Last, we show in vivo that soft materials reduce expression of inflammatory markers and YAP in surrounding macrophages when compared to stiff materials. Together, our studies identify YAP as a key molecule for controlling inflammation and sensing stiffness in macrophages and may have broad implications in the regulation of macrophages in health and disease., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Purpose of Review: The tumor microenvironment (TME) is an amalgam of multiple dysregulated biophysical cues that can alter cellular behavior through mechanotransductive signaling and epigenetic modifications. Through this review, we seek to characterize the extent of biophysical and epigenetic regulation of cancer stemness and tumor-associated immune cells in order to identify ideal targets for cancer therapy., Recent Findings: Recent studies have identified cancer stemness and immune action as significant contributors to neoplastic disease, due to their susceptibility to microenvironmental influences. Matrix stiffening, altered vasculature, and resultant hypoxia within the TME can influence cancer stem cell (CSC) and immune cell behavior, as well as alter the epigenetic landscapes involved in cancer development., Summary: This review highlights the importance of aberrant biophysical cues in driving cancer progression through altered behavior of CSCs and immune cells, which in turn sustains further biophysical dysregulation. We examine current and potential therapeutic approaches that break this self-sustaining cycle of disease progression by targeting the presented biophysical and epigenetic signatures of cancer. We also summarize strategies including the normalization of the TME, targeted drug delivery, and inhibition of cancer-enabling epigenetic players., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest.

DNA methylation is a heritable epigenetic modification that plays an essential role in mammalian development. Genomic methylation patterns are dynamically maintained, with DNA methyltransferases mediating inheritance of methyl marks onto nascent DNA over cycles of replication. A recently developed experimental technique employing immunoprecipitation of bromodeoxyuridine labeled nascent DNA followed by bisulfite sequencing (Repli-BS) measures post-replication temporal evolution of cytosine methylation, thus enabling genome-wide monitoring of methylation maintenance. In this work, we combine statistical analysis and stochastic mathematical modeling to analyze Repli-BS data from human embryonic stem cells. We estimate site-specific kinetic rate constants for the restoration of methyl marks on >10 million uniquely mapped cytosines within the CpG (cytosine-phosphate-guanine) dinucleotide context across the genome using Maximum Likelihood Estimation. We find that post-replication remethylation rate constants span approximately two orders of magnitude, with half-lives of per-site recovery of steady-state methylation levels ranging from shorter than ten minutes to five hours and longer. Furthermore, we find that kinetic constants of maintenance methylation are correlated among neighboring CpG sites. Stochastic mathematical modeling provides insight to the biological mechanisms underlying the inference results, suggesting that enzyme processivity and/or collaboration can produce the observed kinetic correlations. Our combined statistical/mathematical modeling approach expands the utility of genomic datasets and disentangles heterogeneity in methylation patterns arising from replication-associated temporal dynamics versus stable cell-to-cell differences., Competing Interests: The authors have declared that no competing interests exist.

Macrophages perform critical functions for homeostasis and immune defense in tissues throughout the body. These innate immune cells are capable of recognizing and clearing dead cells and pathogens, and orchestrating inflammatory and healing processes that occur in response to injury. In addition, macrophages are involved in the progression of many inflammatory diseases including cardiovascular disease, fibrosis, and cancer. Although it has long been known that macrophages respond dynamically to biochemical signals in their microenvironment, the role of biophysical cues has only recently emerged. Furthermore, many diseases that involve macrophages are also characterized by changes to the tissue biophysical environment. This review will discuss current knowledge about the effects of biophysical cues including matrix stiffness, material topography, and applied mechanical forces, on macrophage behavior. We will also describe the role of molecules that are known to be important for mechanotransduction, including adhesion molecules, ion channels, as well as nuclear mediators such as transcription factors, scaffolding proteins, and epigenetic regulators. Together, this review will illustrate a developing role of biophysical cues in macrophage biology, and also speculate upon molecular targets that may potentially be exploited therapeutically to treat disease., (©2019 Society for Leukocyte Biology.)

Following online publication of this article, the Gene Expression Omnibus records corresponding to accession codes GSM2406773, MN-d6, and GSM2406772, MN-d14, listed in the data availability statement were deleted. The data are now available under accession codes GSM3039355, WGBS_hESC_WT_D6_R4 (MN day 6), and GSM3039351, WGBS_hESC_WT_D14_R4 (MN day 14), and the data availability statement has been updated with the new accession codes in the HTML and PDF versions of the article.

Cytosine methylation is widespread among organisms and essential for mammalian development. In line with early postulations of an epigenetic role in gene regulation, symmetric CpG methylation can be mitotically propagated over many generations with extraordinarily high fidelity. Here, we combine BrdU labeling and immunoprecipitation with genome-wide bisulfite sequencing to explore the inheritance of cytosine methylation onto newly replicated DNA in human cells. Globally, we observe a pronounced lag between the copying of genetic and epigenetic information in embryonic stem cells that is reconsolidated within hours to accomplish faithful mitotic transmission. Populations of arrested cells show a global reduction of lag-induced intermediate CpG methylation when compared to proliferating cells, whereas sites of transcription factor engagement appear cell-cycle invariant. Alternatively, the cancer cell line HCT116 preserves global epigenetic heterogeneity independently of cell-cycle arrest. Taken together, our data suggest that heterogeneous methylation largely reflects asynchronous proliferation, but is intrinsic to actively engaged cis-regulatory elements and cancer.

Despite decades of effort, little progress has been made to improve the treatment of cancer metastases. To leverage the central role of the mechanoenvironment in cancer metastasis, we present a mechanoresponsive cell system (MRCS) to selectively identify and treat cancer metastases by targeting the specific biophysical cues in the tumor niche in vivo. Our MRCS uses mechanosensitive promoter-driven mesenchymal stem cell (MSC)-based vectors, which selectively home to and target cancer metastases in response to specific mechanical cues to deliver therapeutics to effectively kill cancer cells, as demonstrated in a metastatic breast cancer mouse model. Our data suggest a strong correlation between collagen cross-linking and increased tissue stiffness at the metastatic sites, where our MRCS is specifically activated by the specific cancer-associated mechano-cues. MRCS has markedly reduced deleterious effects compared to MSCs constitutively expressing therapeutics. MRCS indicates that biophysical cues, specifically matrix stiffness, are appealing targets for cancer treatment due to their long persistence in the body (measured in years), making them refractory to the development of resistance to treatment. Our MRCS can serve as a platform for future diagnostics and therapies targeting aberrant tissue stiffness in conditions such as cancer and fibrotic diseases, and it should help to elucidate mechanobiology and reveal what cells "feel" in the microenvironment in vivo., (Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Biochemical factors can help reprogram somatic cells into pluripotent stem cells, yet the role of biophysical factors during reprogramming is unknown. Here, we show that biophysical cues, in the form of parallel microgrooves on the surface of cell-adhesive substrates, can replace the effects of small-molecule epigenetic modifiers and significantly improve reprogramming efficiency. The mechanism relies on the mechanomodulation of the cells' epigenetic state. Specifically, decreased histone deacetylase activity and upregulation of the expression of WD repeat domain 5 (WDR5)--a subunit of H3 methyltranferase--by microgrooved surfaces lead to increased histone H3 acetylation and methylation. We also show that microtopography promotes a mesenchymal-to-epithelial transition in adult fibroblasts. Nanofibrous scaffolds with aligned fibre orientation produce effects similar to those produced by microgrooves, suggesting that changes in cell morphology may be responsible for modulation of the epigenetic state. These findings have important implications in cell biology and in the optimization of biomaterials for cell-engineering applications.

Background/purpose: Neurological function in patients with myelomeningocele (MMC) is limited even after prenatal repair. Neural crest stem cells (NCSCs) can improve neurological function in models of spinal cord injury. We aimed to evaluate the survival, integration, and differentiation of human NCSCs derived from induced pluripotent stem cells (iPSC-NCSCs) in the fetal lamb model of MMC., Methods: Human iPSCs derived from skin fibroblasts were differentiated into NCSCs in vitro, mixed with hydrogel, and seeded on nanofibrous scaffolds for surgical transplantation. Fetal lambs (n=2) underwent surgical MMC creation and repair with iPSC-NCSC seeded scaffolds. Gross necropsy and immunohistochemistry were performed at term., Results: IPSC-NCSCs expressed NCSC markers, maintained > 95% viability, and demonstrated neuronal differentiation in vitro. Immunohistochemical analysis of repaired spinal cords thirty days after transplantation demonstrated the co-localization of human nuclear mitotic apparatus protein (NuMA) and Neurofilament M subunit (NFM) in the area of spinal cord injury. No gross tumors were identified., Conclusions: Human iPSC-NCSCs survived, integrated, and differentiated into neuronal lineage in the fetal lamb model of MMC. This is the first description of human stem cell engraftment in a model of fetal MMC and supports the concept of using NCSCs to address spinal cord damage in MMC., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Spinal cord injury (SCI) remains a major challenge for regenerative medicine. Following SCI, axon growth inhibitors and other inflammatory responses prevent functional recovery. Previous studies have demonstrated that rolipram, an anti-inflammatory and cyclic adenosine monophosphate preserving small molecule, improves spinal cord regeneration when delivered systemically. However, more recent studies showed that rolipram has some adverse effects in spinal cord repair. Here, we developed a drug-delivery platform for the local delivery of rolipram into the spinal cord. The potential of drug-eluting microfibrous patches for continuous delivery of high and low-dose rolipram concentrations was characterized in vitro. Following C5 hemisections, athymic rats were treated with patches loaded with low and high doses of rolipram. In general, animals treated with low-dose rolipram experienced greater functional and anatomical recovery relative to all other groups. Outcomes from the high-dose rolipram treatment were similar to those with no treatment. In addition, high-dose treated animals experienced reduced survival rates suggesting that systemic toxicity was reached. With the ability to control the release of drug dosage locally within the spinal cord, drug-eluting microfibrous patches demonstrate the importance of appropriate local release-kinetics of rolipram, proving their usefulness as a therapeutic platform for the study and repair of SCI., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background/purpose: Spinal cord damage in myelomeningocele (MMC) results from abnormal cord development and subsequent local trauma. Prenatal surgery prevents additional neural injury. However, existing damage is not reversed. Biodegradable nanofibrous scaffolds (NSs) promote regeneration of neural tissues. They mimic the microtopography of the extracellular matrix and guide tissue formation and organization. The purpose of this pilot study was to evaluate the practicality and safety of using biodegradable NS as a regenerative device in prenatal MMC repair., Methods: Two fetal lambs underwent a surgically induced MMC defect followed by open fetal repair using aligned biodegradable NS. Lambs were killed at day 138. Spinal cords were examined for inflammation or fibrosis and stained for spinal cord architecture, myelin, and neuron cell bodies., Results: Prenatal repair with NS demonstrated technical feasibility. There was no evidence of a surrounding inflammatory response or foreign-body reaction to the scaffold., Conclusion: Biodegradable NS can be used surgically for the prenatal repair of MMC in a large animal model and does not appear to elicit an inflammatory or fibrotic reaction in fetal tissue. Further studies will determine their potential for neural cell infiltration, delivery of growth factors, drugs or stem cells, and functional recovery greater than standard repair., (Copyright © 2011 Elsevier Inc. All rights reserved.)