Successful Implantation of Schwann Cells in Acellular Muscles

Abstract

Acellular muscle grafts can support axonal regeneration over short gaps. Due to the lack of viable Schwann cells in the grafts, failure of regeneration is evident with increasing gap lengths. To create a biological nerve conduit, Schwann cells were implanted into acellular muscle. The grafts were then incubated in vitro and assessed histologically and morphometrically. For cultivation of the Schwann cells, rat sciatic nerves were allowed to predegenerate to obtain a high cell yield. Rat gracilis muscles were harvested and made acellular by a liquid nitrogen treatment. After Schwann cell implantation, the muscles were incubated in vitro for 2, 5, and 7 days. S100-immunostaining, NGF, and N-cadherin, characterized the Schwann cells within the muscle. Viability was assessed by fluoresceine-fluorescence staining. Proliferation was determined by BrdU-DNA incorporation. Cell implantation did not to affect Schwann cell viability. Cells were seen throughout the entire length of the muscle basal lamina. They aligned and formed a cell column. Immunostained for S-100, implanted cells showed 100 percent staining. N-cadherin and NGF were expressed by all of the S-100 positive cells. Predegeneration is considered to be a highly efficacious method, if a high yield of activated Schwann cells is required. The successful implantation of the cells into an acellular muscle provides the possibility of a biologic conduit, offering the advantage of large basal lamina tubes serving as a pathway for regenerating axons. It also provides the beneficial effects of viable Schwann cells that produce neurotrophic and neurotropic factors to support axonal regeneration. Functional outcomes require evaluation in further in vivo studies.

Use of poly(DL-lactide-ε-caprolactone) membranes and mesenchymal stem cells from the Wharton's jelly of the umbilical cord for promoting nerve regeneration in axonotmesis: In vitro and in vivo analysis

“…Schwann cell transplantation enhances axon outgrowth both in vitro ( Schlosshauer et al, 2003) and in vivo ( Keilhoff et al, 2006). Transplantation of viable SCs offers better results than the sheer release of growth factors, because SCs have the above mentioned regeneration promoting effect ( Bhatheja and Field, 2006;Fansa et al, 1999;Hall, 1978;Ide, 1996;Madduri and Gander, 2010;Muir, 2010;Schmitte et al, 2010). The generation of sufficient amounts of SCs for auto-transplantation, however, requires a significant time for cell culture.…”

Cryopreservation of peripheral nerve grafts

“…The axon-Schwann cell attachment is mediated by immunoglobulin and cadherin superfamily molecules. 12,17,22 Furthermore, Schwann cells also produce basal lamina components, such as collagen IV and laminin. 2,28 Among the adhesion molecules, laminin, as a physiological constituent of the basal lamina, is the most potent one for promoting axonal outgrowth.…”

“…13,15,27 Recent studies, however, indicate that it is possible to create nerve graft substitutes from viable, cultured Schwann cells and biological matrices serving as scaffolds for the regenerating nerve. 12 The use of nerve allografts has been the subject of extensive experimental and, more recently, clinical research. Nerve allografts may be available to an unlimited extent but will undergo rejection and thus require the continuous use of immunosuppressive drugs.…”

“…Nerve allografts may be available to an unlimited extent but will undergo rejection and thus require the continuous use of immunosuppressive drugs. 12 The functional outcome after rejection is not yet clear. 3 Therefore, at the moment, allogenic nerve grafting remains limited to special cases.…”

“…8 With more specific immunosuppressive drugs offering fewer side effects, however, this might certainly change in the near future. 12 The utilization of viable biological nerve graft substitutes and allografts raises the problem of nerve storage. We have previously shown that preservation of nerve segments subjected to cold ischemia of 4°C in Dulbecco's modified eagle medium (DMEM) is possible for up to 3 days without significant impairment of nerve regeneration.…”