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Diabetes mellitus causes severe impairment in the cutaneous wound healing process, which has led to extensive research striving to establish new treatments. In this work, we describe the effects of chitosan hydrogels functionalized with either unfractionated heparin or bemiparin (a low molecular weight heparin, LMWH) as topical treatments in an experimental diabetic wound healing model. Although wound morphometry showed similar values at the end of the study, microscopic analyses revealed impaired healing in diabetic animals in terms of inflammation and tissue formation. However, both types of loaded hydrogels accelerated inflammation resolution and improved the epithelialization process, while showing a neodermal thickness similar to that of nondiabetic animals. Immunohistochemistry analyses revealed an intermediate response in macrophage evolution between diabetic and nondiabetic controls in the treated groups, as well as enhanced collagenization and myofibroblast progression patterns. However, these changes were not accompanied by differences among groups in collagen I, III and TGF-β1 gene expression. Functionalized hydrogels improved diabetes-associated impaired wound healing, thus promoting the progression of the process and inducing the formation of high-quality cicatricial tissue. Although the beneficial healing effect observed after topical treatment with chitosan hydrogels loaded with bemiparin or unfractionated heparin was similar, the chitosan hydrogel loaded with bemiparin is the preferred choice as it exhibited high-quality tissue in the neoformed dermal tissue., (Copyright © 2020 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

The growth hormone is involved in skin homeostasis and wound healing. We hypothesize whether it is possible to improve pressure ulcer (PU) healing by locally applying the recombinant human growth hormone (rhGH) in a human skin mouse model. Non-obese diabetic/severe combined immunodeficient mice ( n = 10) were engrafted with a full-thickness human skin graft. After 60 days with stable grafts, human skin underwent three cycles of ischemia-reperfusion with a compression device to create a PU. Mice were classified into two groups: rhGH treatment group ( n = 5) and control group ( n = 5). In the rhGH group for local intradermal injections, each had 0.15 mg (0.5IU) applied to the PU edges, once per week for four weeks. Evaluation of the wound healing was conducted with photographic and visual assessments, and histological analysis was performed after complete wound healing. The results showed a healing rate twice as fast in the rhGH group compared to the control group (1.25 ± 0.33 mm2/day versus 0.61 ± 0.27 mm2/day; p -value < 0.05), with a faster healing rate during the first 30 days. The rhGH group showed thicker skin (1953 ± 457 µm versus 1060 ± 208 µm; p -value < 0.05) in the repaired area, with a significant decrease in collagen type I/III ratio at wound closure (62 days, range 60-70). Local administration of the rhGH accelerates PU healing in our model. The rhGH may have a clinical use in pressure ulcer treatment.

Background: Adhesions commonly appear in patients after abdominal surgery, with considerable individual variation in adhesion composition and severity of the repair process. Here, we address the influence of transforming growth factor (TGF)-β3 and betaglycan in this response, in relation to TGF-β1, in an adhesiogenic rabbit model., Materials and Methods: Omental adhesions were recovered 3, 7, 14, and 90 d after the implantation of a polypropylene mesh on the parietal peritoneum in New Zealand White rabbits. Omentum from nonoperated animals served as control. Tissue specimens were examined for TGF-β3 and TGF-β1 (Western blotting, reverse transcription-polymerase chain reaction), and TGF-β1:TGF-β3 messenger RNA and protein expression ratios were analyzed. Immunohistochemical detection of TGF-β3 and betaglycan was performed., Results: Injury to the omentum led to mobilization of TGF-β3 and betaglycan-expressing cells from milky spots. Fibrous zones in adhesions were simultaneous to the presence of TGF-β1 and the membrane-bound form of betaglycan (7-d adhesions), whereas soluble betaglycan appeared in TGF-β1-positive areas showing limited fibrosis (3-d adhesions). The elevated expression of TGF-β3 concurrent with the presence of membrane-bound form of betaglycan was observed in zones of adipose regeneration (14-d adhesions), whereas zones of fibrous consistency were negative for TGF-β3., Conclusions: Milky spots on the omentum contain inflammatory/immune cells positive for TGF-β3, TGF-β1, and betaglycan, playing a role in the damaged omentum repair. Our observations support the contribution of TGF-β3 to tissue repair through adipose tissue regeneration and the profibrotic role of TGF-β1 and suggest that these effects on the local wound repair response could be driven by the expression of betaglycan in its soluble or membrane-bound form., (Copyright © 2014 Elsevier Inc. All rights reserved.)

A combination of vascular pathologies and other complicating factors results in chronic wounds which constitute a serious burden for both patients and national health systems, due to prolonged hospital stays, high costs, and prolonged nursing staff dedication. Here we investigate whether proadrenomedullin N-terminal 20 peptide (PAMP), a naturally occurring peptide of the skin with antimicrobial and proangiogenic properties, either alone or in combination with autologous skeletal muscle stem/progenitor cells, acts as a wound healing factor. The rabbit ear was chosen as a test system, since it offers a reliable model for normoxic and ischemic wounds. Topical treatments with PAMP, stem/progenitor cells, or a combination of both, resulted in significant improvements of healing, when compared to untreated wounds. PAMP was very effective in promoting reepithelialization and angiogenesis, whereas treatment with stem/progenitor cells alone resulted in less wound contraction. Interestingly, the combination of PAMP and stem/progenitor cells, while maintaining angiogenic potency, reverted to the contraction levels observed in the untreated controls. Under ischemic conditions, generalized necrosis of the dermis and the underlying cartilage was observed in untreated wounds. Treatments of these wounds with PAMP or stem/progenitor cells allowed a timely recovery. In conclusion, PAMP either alone or in combination with autologous stem/progenitor cells may provide a useful tool for improving wound healing both in normoxic and ischemic conditions.

Background: This study was designed to assess the early host tissue incorporation of several polypropylene lightweight (PP-LW) meshes used to repair abdominal wall defects and to correlate collagen deposition with the biomechanical response shown by PP-LW versus polypropylene heavyweight (PP-HW) meshes., Methods: Ventral hernial defects (7 x 5 cm) were created in the anterior abdominal wall of New Zealand rabbits and repaired by fixing PP-LW mesh of different pore sizes or a low porosity HW mesh to the edges of the defect. Rabbits were killed 14 days after implant, and specimens were taken from the central mesh area to examine collagen deposition by light microscopy, real time reverse transcription polymerase chain reaction, immunohistochemistry, and Western blotting. The biomechanical resistance of the biomaterials was also assessed., Results: All the materials showed excellent incorporation in host tissue. Relative amounts of collagen III mRNA were considerably higher than collagen I mRNA. Higher collagen I and III mRNA levels were noted for pore sizes equal to or greater than 3.45 +/- 0.19 mm(2) (Ultrapro/Optilene Elastic. These two meshes showed significantly higher levels of collagen III than Parietene and Surgipro with smaller pores. Biomechanical resistance values for Optilene were significantly higher than those recorded for Surgipro and Parietene., Conclusions: (a) LW meshes of pore size larger than 3 mm(2) induced the genetic overexpression of collagen types I and III; (b) the larger pore-sized LW meshes induced more collagen type III deposition and its faster conversion to collagen I; (c) Optilene, the most porous LW mesh examined, showed the greatest tensile strength 14 days after implant.

In many diseases wound healing is impaired. This study was designed to establish whether the healing process in diabetes could be improved using a site-specific polymer delivery system containing hGH. The system was first optimized in in vitro experiments performed on cultured fibroblasts taken from healthy and diabetic rats and then tested in an incisional wound model created in the diabetic Wistar rat. In the in vitro experiments using cultured fibroblasts, cell viability, growth, and proliferation were determined, along with polymer degradation, hormone release rates and the expression of TGFbeta1 in the culture medium. For the in vivo experiments, polymer discs with/without GH were inserted through 3 cm incisions made on the backs of the animals. Wound specimens were obtained 7 and 30 days after surgery to evaluate inflammatory/apoptotic cells, metalloprotease expression and neoangiogenesis using microscopy and immunohistochemical techniques. The local administration of GH using a polymer delivery system did not affect the normal wound healing process. Conversely, when used in diabetic animals, epidermal and dermal repair was expedited. Our findings indicate that GH induces cell proliferation, enhances CD4(+) infiltration; increases extracellular matrix protein deposition; stimulates angiogenesis; and diminishes apoptosis at the diabetic wound site. These effects give rise to a comparable wound healing process to that observed in healthy animals.

Stem cells derived from adult tissues may serve as cell therapy to enhance the healing process in skin wounds. This study was designed to evaluate the use of autologous muscle-derived stem cells in an experimental skin wound model in terms of their efficiency at promoting tissue repair/regeneration. Muscle-derived cells obtained from the dorsal muscle of New Zealand rabbits were cultured in vitro for 2 weeks. The cell population was identified using the satellite markers CD34, m-cadherin and Myf5, and the proliferative capacity of the adult stem cells was determined. The population was then fluorescently labeled with PKH26 and seeded onto a circular 2 cm diameter defect created on the dorsal side of the ear of the rabbit from which the cells had been harvested. Similar defects on the contra lateral ears were left untreated to form the control group. Fourteen days later, specimens were taken for light, transmission, and scanning electron microscopy, as well as for immunolabeling with antibodies against vimentin, alpha-actin, desmin, myosin, fibronectin, and cytokeratin 14. Areas of wound contraction and reepithelialization were determined by image analysis. Wound contraction was significantly greater in the control than the treatment group (p<0.05); control specimens also showed more myosin expression. Reepithelialized areas were significantly greater in the treatment group (p<0.05). Control wounds showed nonepithelialized areas and inflammatory granulation tissue. Reepithelialization occurred as epidermal tongues of fusiform cells. Our findings indicate that the use of autologous stem cells on skin wounds expedites and improves the organism's natural healing process.

Controlled release systems for drugs, hormones and growth factors can be particularly useful in tissue repair processes. These systems act as a biodegradable support containing the substance to be delivered, allowing their gradual release. In the past years, the local application of growth factors has acquired special relevance as a therapeutic option for use in subjects who show deficient tissue scarring, the hormone dose being the limiting factor for its success. In this study, the in vitro biocompatibility of a copolymer formed by vinylpyrrolidone and 2-hydroxyethyl methacrylate, used as an administration vehicle for hGH, was evaluated. The system was then tested in vivo in terms of its capacity for healing incisional wounds in healthy and diabetic rats. For the in vitro studies, polymer and hormone degradation rates were determined, and polymer biocompatibility was evaluated in fibroblast cultures. In the in vivo experiments, an incision was made in the back of the animals, and polymers discs with/without hGH, were introduced in the aperture. Morphological, immunohistochemical and morphometric evaluations were performed on wound tissue specimens 3-10 days after surgery. In vitro, the polymer was found to be biodegradable and showed no toxic effects on fibroblasts, the hormone being slowly released to the culture medium. In untreated diabetic rats, a delayed skin scarring and cell response were observed, compared to that noted in healthy animals. Skin closure, keratinisation and fibrosis occurred earlier in the presence of the polymer-hGH system. The use of this co-polymer as an administration vehicle for hGH improves the wound scarring process in the pathological setting of diabetes.

The present study compared the performance of three composite prostheses used to repair abdominal wall defects in rabbits. Two of them [Parietex Compositereg (PC) and Composixreg (CS)] are commonly used in clinical practice and one was designed by the present team (PL-PU99). At 14 and 90 days postimplant, specimens were obtained for morphological, macrophage response (RAM-11) and morphometric and biomechanical analysis. The prosthetic area covered by adhesions was significantly greater (p < 0.05) in the CS group (6.83 plus minus 2.31 cm(2)) than in PC (0.11 +/- 0.02 cm(2)) or PL-PU99 (0.10 +/- 0.07 cm(2)). At 14 days, it was observed a homogeneous, organized, well-vascularized neoperitoneum that was significantly thicker (p < 0.05) in PL-PU99. Except in the CS implants, this layer was covered by a continuous mesothelium. All three composites achieved good recipient tissue integration. Highest macrophage levels were recorded at 14 days with significantly higher values in the PL-PU99 prosthesis. Biomechanical strength was significantly greater (p < 0.05) in CS at two weeks postimplant, but it was similar at 90 days. These findings suggest that the three composites show ideal integration with host tissue, along with similar biomechanical strength at 90 days, and significantly higher adhesion formation is induced by the CS prosthesis, possibly due to incomplete mesothelialization of the lower prosthetic surface., (Copyright 2002 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 63: 182--190, 2002; DOI 10.002/jbm.10123)

Objective: To compare the behaviour of two composite biomaterials in rabbit peritoneum., Design: Animal study., Setting: Faculty of Medicine, University of Alcalá, Spain., Animals: 14 white New Zealand white rabbits divided into 2 groups of 7 each., Interventions: Defects (7 x 5 cm) involving all the layers of the abdominal wall were created and repaired using Parietex Composite or Vypro prostheses. Fourteen days after implantation, prosthetic specimens were examined by microscopy, and morphometric and biomechanical analysis., Main Outcome Measures: Infection, healing, development of adhesions, and histological appearance of the interface., Results: Firm adhesions were detected after the implant of Vypro while adhesion were loose in the Parietex group. The mean (SD) prosthetic surface area covered by adhesions was significantly greater in the Vypro group 22.3 (2.8) compared with 0.2 (0.02), p <0.01). The neoperitoneum formed after the implant of Parietex was well-organised and homogeneous and covered by a typical mesothelium, while in the Vypro it was disorganised, with a rough texture composed of prosthetic filaments and nodes. The neoperitonum was thicker in the Parietex group 154.0 (5.4) compared with 50.8 (2.3), p <0.05) while higher biomechanical resistance values were recorded in the Vypro group 30.4 (1.9) compared with 15.0 (2.73), p <0.05)., Conclusions: While both biomaterials integrated well with tissue, Parietex behaved better at the peritoneal interface.

A comparative study has been carried out dealing with the vascular healing process in two experimental vascular graft models to determine the differences or similarities between the two. One of the models consisted of the use of arterial autografts and the other of the implantation of vascular microprostheses of polytetrafluoroethylene (PTFE). The common iliac artery of female Sprague-Dawley rats was used. The length of the grafts in both models was 5 mm. A microsurgical technique was employed, and anticoagulant and antibiotic therapies were not used. The results were studied using light microscopy, transmission and scanning electron microscopies, autoradiography, and immunohistochemistry. A patency of 100% was obtained in the arterial autografts, and 87.6% in the PTFE implants. The histopathological findings were as follows: a) the mechanisms of immediate postgrafting response were similar, with marked presence of fibrin and platelet deposition in the form of a nonthrombogenic monolayer; b) a "neoadventitia" formed over the implant in both models; c) the endothelialisation was complete in both types of grafts 2 to 3 weeks after implantation; d) an intimal hyperplastic response appeared in both, although at different times (in the first week in the autografts and at one month with the PTFE); e) white cell accumulation was significantly greater on the PTFE luminal surface than on the autograft. The intimal hyperplasia was formed mainly by secretory myocytes in the autografts, while in the PTFE implants, fibrosis predominated.

In the present work, the repairing response of the iliac arterial wall is studied after carrying out autografts in segments of these vessels. The formation of the intimal hyperplasia, which occurred in all the cases, was followed at the biochemical level (tritium thymidine incorporation) and with light and electron microscopy. The adventitial layer showed great activity during the repairing process. We believe that it plays an important role not only in neoadventitial formation, but also in myointimal raising.

Background/Aims: This study was designed to evaluate the extent of adhesion formation to prostheses fixed with spiral tacks and to establish whether the use of Ringer’s lactate or icodextrin could prevent these adhesions. Methods:24New Zealand white rabbits weighing around 3,000 g were implanted with a 7 × 5 cm patch of ePTFE (DualMesh®) through amidline laparotomy. The prosthesis was fixed to the intact peritoneum using spiral tacks. Three study groups were established according to whether the animals were: implanted with ePTFE fixed with spiral tacks or implanted with ePTFE fixed with spiral tacks and simultaneously administered Ringer’s lactate or 4% icodextrin in the peritoneal cavity. Adhesion formation and prosthetic behavior at the prosthesis/peritoneal interface were evaluated and quantified by sequential laparoscopy performed at 3, 7 and 14 days. Results: Adhesions generally formed on the tacks and were classified as the fully integrated type. No significant differences were observed in terms of the extent of adhesions or of neoperitoneal thickness between control animals and those receiving Ringer’s lactate or icodextrin. Conclusions: (a)Prosthesis-fixing tacks induced adhesions; (b) the use of substances such as icodextrin or Ringer’s lactate does not seem to diminish adhesion formation, and (c) the use of icodextrin offered no benefits over that of Ringer’s lactate solution. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]