Human Platelet-Rich Plasma- and Extracellular Matrix-Derived Peptides Promote Impaired Cutaneous Wound Healing In Vivo

Previous work in our laboratory has described several pro-angiogenic short peptides derived from endothelial extracellular matrices degraded by bacterial collagenase. Here we tested whether these peptides could stimulate wound healing in vivo. Our experiments demonstrated that a peptide created as combination of fragments of tenascin X and fibrillin 1 (comb1) applied into cranial dermal wounds created in mice treated with cyclophosphamide to impair wound healing, can improve the rate of wound closure. Furthermore, we identify and characterize a novel peptide (UN3) created and modified from two naturally-occurring peptides, which are present in human platelet-rich plasma. In vitro testing of UN3 demonstrates that it causes a 50% increase in endothelial proliferation, 250% increase in angiogenic response and a tripling of epithelial cell migration in response to injury. Results of in vivo experiments where comb1 and UN3 peptides were added together to cranial wounds in cyclophosphamide-treated mice leads to improvement of wound vascularization as shown by an increase of the number of blood vessels present in the wound beds. Application of the peptides markedly promotes cellular responses to injury and essentially restores wound healing dynamics to those of normal, acute wounds in the absence of cyclophosphamide impairment. Our current work is aimed at understanding the mechanisms underlying the stimulatory effects of these peptides as well as identification of the cellular receptors mediating these effects.National Institutes of Health (U.S.) (Grant EY15125)National Institutes of Health (U.S.) (Grant EY19533)Wound Care Partners, LL

The effect of an autologous cellular gel-matrix integrated implant system on wound healing

<p>Abstract</p> <p>Background</p> <p>This manuscript reports the production and preclinical studies to examine the tolerance and efficacy of an autologous cellular gel-matrix integrated implant system (IIS) aimed to treat full-thickness skin lesions.</p> <p>Methods</p> <p>The best concentration of fibrinogen and thrombin was experimentally determined by employing 28 formula ratios of thrombin and fibrinogen and checking clot formation and apparent stability. IIS was formed by integrating skin cells by means of the <it>in situ </it>gelification of fibrin into a porous crosslinked scaffold composed of chitosan, gelatin and hyaluronic acid. The <it>in vitro </it>cell proliferation within the IIS was examined by the MTT assay and PCNA expression. An experimental rabbit model consisting of six circular lesions was utilized to test each of the components of the IIS. Then, the IIS was utilized in an animal model to cover a 35% body surface full thickness lesion.</p> <p>Results</p> <p>The preclinical assays in rabbits demonstrated that the IIS was well tolerated and also that IIS-treated rabbit with lesions of 35% of their body surface, exhibited a better survival rate (p = 0,06).</p> <p>Conclusion</p> <p>IIS should be further studied as a new wound dressing which shows promising properties, being the most remarkable its good biological tolerance and cell growth promotion properties.</p

Inclusões de quitosana no subcutâneo de rato: avaliação clínica, histológica e morfométrica Chitosan inclusions in the subcutaneous space of rats: clinic, histologic and morphometric evaluation

FUNDAMENTOS: A quitosana é polímero derivado da quitina, com vários tipos de aplicação na área médica. OBJETIVO: Avaliar a biocompatibilidade de membranas de quitosana no subcutâneo de ratos. MÉTODOS: Foram utilizados 20 ratos "Wistar" machos, nos quais foram implantadas membranas de quitosana, na região mediana dorsal. Os animais foram sacrificados: sete, 15, 30 e 60 dias após a cirurgia, tendo sido avaliados clinicamente durante o período experimental e com fotodocumentação no momento do sacrifício. Após o sacrifício, as membranas e tecidos adjacentes foram removidos e preparados para exame histológico e morfométrico. RESULTADOS: Nenhum animal apresentou efeitos adversos que pudessem ser atribuídos à implantação das membranas. O exame histológico mostrou que as inclusões são lisas e homogêneas e não são colonizadas por células do hospedeiro, sendo circundadas por pseudocápsula composta por fibroblastos e células inflamatórias. A morfometria da pseudocápsula revelou espessura semelhante durante todo o período experimental (P>0,05). CONCLUSÃO: A quitosana pode ser opção para uso como implante não integrado. Novos estudos devem ser realizados para comprovar a biocompatibilidade a longo prazo.<br>BACKGROUND: Chitosan is a polymer derivative from chitin applied in many medical specialties. OBJECTIVE:To evaluate the biocompatibility of chitosan membranes used as inclusion material into subcutaneous of rats. METHODS: Twenty male Wistar rats received chitosan membranes into the subcutaneous area of the dorsal medial region. The animals were randomly divided in four groups with 5 animals each, sacrificed on 7th (G1), 15th (G2), 30th (G3) and 60th (G4) postoperative day (PO). All animals were clinically evaluated daily and by photo-documentation at the sacrifice moment. The animals and the material were assessed for evidence of host response by histological and morphometric evaluation of the implants and the surrounding soft tissues. The material was fixed in 10% formalin and then the sections were stained with hematoxylin and eosin. RESULTS: None of animals presented side effects attributable to the implants. The histological evaluation showed smooth and homogeneous inclusions with no host cells inside and were encircled by a pseudocapsule of fibroblasts and inflammatory cells. The morphometric evaluation showed no statistical difference between different groups (P>0.05)