Phenotypical characterization of 6-21-week gestational age human dermis and epidermal cell isolation methods for in vitro studies on epidermal progenitors.

UNLABELLED: Cell banked epidermal skin progenitor cells have the potential to provide an "off-the-freezer" product. Such cells may provide a skin donor area-independent cell-spray grafting therapy for the treatment of burns. We first characterized fetal skin samples of gestational ages ranging from 6 to 21 weeks. As the results suggest that the phenotypic differentiation occurs after 10 weeks, which may complicate follow-up in vitro studies, we developed and compared different cell isolation techniques for human fetal skin-derived epithelial cells from tissue ages 6 to 9 weeks. We initially screened seven methods of characterization, concluding that two methods warranted further investigation: incubating the epidermal tissue in Petri-dishes with culture medium for spontaneous cell outgrowth, and wiping the epidermal tissue onto a dry Petri-dish culture surface followed by adding culture medium. Non-controllable culture contamination with dermal cells was the reason for excluding the other five methods. The results suggest that epidermal cells can be isolated from tissue exhibiting a single homogeneous layer of CK15(+) basal keratinocytes up to week 9. At later gestational ages, the ongoing skin differentiation results in a multi-layer basal structure and progenitors associated with the hair bulb would have to be considered. Spraying the resulting cells with a clinical spray device was successfully demonstrated in an in vitro model. CONCLUSION: Gestational age 6-9 weeks epidermal human fetal skin cells from the basal layer can be reproducibly isolated and transferred into culture for studies on the development of skin cell transplantation therapies.

Macrophage stimulating protein may promote tubular regeneration after acute injury.

Macrophage-stimulating protein (MSP) exerts proliferative and antiapoptotic effects, suggesting that it may play a role in tubular regeneration after acute kidney injury. In this study, elevated plasma levels of MSP were found both in critically ill patients with acute renal failure and in recipients of renal allografts during the first week after transplantation. In addition, MSP and its receptor, RON, were markedly upregulated in the regenerative phase after glycerol-induced tubular injury in mice. In vitro, MSP stimulated tubular epithelial cell proliferation and conferred resistance to cisplatin-induced apoptosis by inhibiting caspase activation and modulating Fas, mitochondrial proteins, Akt, and extracellular signal-regulated kinase. MSP also enhanced migration, scattering, branching morphogenesis, tubulogenesis, and mesenchymal de-differentiation of surviving tubular cells. In addition, MSP induced an embryonic phenotype characterized by Pax-2 expression. In conclusion, MSP is upregulated during the regeneration of injured tubular cells, and it exerts multiple biologic effects that may aid recovery from acute kidney injury.