In Vivo Evaluation of Novel Lab Engineered Tissue in Nerve Repair
Abrielle Prunty, BS1, John Carney, MBA/BS2, Richard Murphy, BS1 and Zeeshan Syedain, PhD1,2, 1Vascudyne, Saint Paul, MN, 2University of Minnesota, Minneapolis, MN
Introduction
Peripheral nerve injury remains a challenging clinical problem to address. The commercially available conduits made from porcine small intestine submucosa (SIS), or bovine cross-linked type I collagen pose multiple challenges: fibrosis from host rejection, immune response, and early collapse. We have developed lab engineered regenerative tissue that has shown in a clinical study to regenerate as a living blood vessel without eliciting an immune response. The purpose of this study was to evaluate nerve regeneration with this novel engineered tissue.
Materials & Methods
The tissue engineered nerve wrap and conduit were developed by lab cultured fibroblasts in a hydrogel and decellularized to create an acellular tissue. The tissue was evaluated for mechanical properties. Microsurgeries were performed with IACUC approval. Rat sciatic nerve model (n=24) was used with explants at 30 and 90 days. Independent researchers monitored foot recovery. Explanted sites were examined grossly, and histopathology was performed.
Results
Engineered tissue exceeded physiological strength and suture retention. Surgically, the tissue handled like native tissue. All surgeries, n=12 nerve wrap and n=12 nerve gap (5mm) went well, and animals had normal recovery. In the critical gap model, 3/5 animals with engineered tissue had full load bearing foot recovery by day seven compared to 1/5 animals in SIS group. 30- and 90-day explants showed more scar tissue around SIS implant compared to the engineered tissue (Fig 1 a&b). Histology showed an immune response of large macrophage clusters around SIS (Fig 1c), but no such response around the engineered tissue (Fig 1d). Evidence of new nerves without scar tissue was seen in the gap model using engineered tissue.
Conclusions
In vascular clinical applications, allogenic acellular engineered tissue has shown to regenerate into living blood vessel without an immune response. In this study, the same tissue was cut into smaller wraps and conduits to assess the benefits in nerve repair applications. The study confirmed engineered tissue does not elicit the same level of immune response and scar tissue formation as current SIS products. Histology confirmed regeneration and potential evidence of nerve regeneration in the critical gap model.
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