Minimally Invasive Muscle Embedding (MIME), Facilitates the Development of Functional Muscle Fibers of Human Cadaveric Origin, in Host Mice

Abstract

BACKGROUNDMinimally Invasive Muscle Embedding (MIME), is a technique developed in our laboratory, to facilitate the development of donor‐cell‐derived muscle fibers in a host muscle. MIME involves passing a sterile needle through a host muscle, and then implanting a segment of donor muscle tissue along with its myogenic satellite cells, in the needle track within the host muscle.METHODSWe validated MIME, by implanting a single extensor digitorum longus (EDL) muscle, from donor mice (N=2), which expressed a red fluorescent protein (RFP), into the left tibialis anterior muscle (TA), of immunodeficient host mice (N=4), which expressed a green fluorescent protein (GFP). In the same host mice, we performed a SHAM procedure on the right TA. In another set of host mice, we implanted by MIME, segments of human cadaveric TA (3 days post‐mortem), or performed a SHAM procedure (N=4 per group). We triggered concerted muscle degeneration and regeneration by injecting 1.2% barium chloride (BACL) into the TAs after MIME or SHAM. We collected TAs at 14 days after implanting RFP+ mouse donor muscle, and at 12 weeks after implanting human donor muscle. We performed histological and physiological assays to compare MIME‐ and SHAM‐treated host TA muscles. We studied histological images with Image J software to obtain quantitative data. We performed statistical analyses (ANOVAs) with SigmaStat or SPSS software.RESULTSIn host TAs implanted with RFP+ mouse EDL, 22±4% and 78±4% muscle fibers were RFP+ and GFP+, respectively. There were no RFP+ fibers in SHAM‐treated muscles. All RFP+ fibers were positive for desmin and dystrophin, and 65±4 % fibers were centrally nucleated. Donor‐derived fibers had multiple sarcomeres and nuclear domains in series. In host TAs implanted with human muscle, ~30% of the host muscle was of donor origin (GFP−), and the majority of GFP− fibers were positive for human‐specific markers. The contractile torque produced by MIME and SHAM TAs was not statistically different at 12 weeks post‐MIME, and there was no statistical difference compared to torque produced before MIME or SHAM procedures. Data are reported as Mean±SEM. P<0.05 considered significant.CONCLUSIONThrough MIME, we confirm that, human cadaveric muscle, implanted up to 3 days post‐mortem, can generate donor‐derived muscle fibers that are morphologically and functionally healthy. Our studies are translationally‐relevant; since MIME can be adapted to implant myogenic tissue of human cadaveric origin, to generate donor‐derived muscle fibers in human recipients (example: patients with muscle loss from muscle disease, trauma, or aging), with suitable immunosuppressive and rehabilitative therapies.Support or Funding InformationFunded by a Pilot Grant from the Alliance for Regenerative Rehabilitation Research and Training (AR3T), NIH 1R03HD091648‐01 and 5R03HD091648‐02 from NICHD, and a Faculty Startup Package and FRAP award from Wayne State University, to JAR. De‐identified, cadaveric human muscle tissue, was made available through the Body Bequest Program at Wayne State University. MIME facilitates donorderived myogenesisimageMIME facilitates donorderived myogenesisThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.