Rationale: Traumatic nerve injuries are a major clinical challenge. Tissue engineering using a combination of nerve conduits and cell based therapies represents a promising approach to nerve repair.
Objectives: The aim of this study is to examine the regeneration potential of human adipose-derived stem cells (hASCs) after transplantation in a non-autogenous setting and to compare them with autogenous rat ASCs (rASCs) for early peripheral nerve regeneration. Furthermore, the use of MRI to assess the continuous process of nerve regeneration was elaborated.
Methods: The sciatic nerve injury model in female Sprague Dawley rats was applied and a 10mm gap created by using a fibrin conduit seeded with the following cell types: rASCs, Schwann cell (SC)-like cells from rASC, rat SCs (rSCs), hASCs from the superficial and deep abdominal layer as well as human stromal vascular fraction (SVF) (1 x 106 cells). As a negative control group culture medium only was used. After two weeks, nerve regeneration was assessed by immunocytochemistry. Furthermore, MRI was performed after two and four weeks to monitor nerve regeneration.
Results: Autogenous ASCs and SC-like cells led to accelerated peripheral nerve regeneration whereas the human stem cell groups displayed inferior results. Nevertheless, positive trends could be observed for hASCs from the deep abdominal layer. By using a clinical 3T MRI scanner, we were able to visualize the graft as a small black outline and small hyperintensity indicating the regenerating axon front. Furthermore, a strong correlation was found between the length of regenerating axon front measured by MRI and the length measured by immunocytochemistry (r=0.74, p=0.09).
Conclusion: We successfully transplanted and compared human and autologous stem cells for peripheral nerve regeneration in a rat sciatic nerve injury model. Furthermore, we were able to implement the clinical 3T MRI scanner to monitor the efficacy of cellular therapy over time.