The effect of human umbilical cord-derived mesenchymal stem cell conditioned medium on the peripheral nerve regeneration of injured rats

Peripheral nerve injury occurs in 3-10% of extremity trauma patients. Mesenchymal stem cells (MSCs) have been used in injuries. Nevertheless, the mechanism of human umbilical cord MSCs (UC-MSCs) and/or their conditioned medium (CM) capacity in regenerating peripheral nerves is not widely known. This study is aimed to determine the mechanism, of UC-MSC CM in improving the structure and function of the nerves after peripheral nerve injury. This experimental study used Sprague-Dawley rats. The experimental animals were divided into 3 groups: control (Sham [SH]), and treatment groups (standard therapy [ST] and CM). The sciatic nerve of the SH group was not injured (only exposed and closed), while those of the ST and CM groups were both cut and given standard sutures. The CM group was treated with topical UC-MSCs CM. The study was divided into two stages i.e. a short-term and long-term research to check the parameters at 7 and 70 days post injury (dPI), respectively. The parameters collected were motor functions (walking analysis), electrophysiology and structural parameters. There were signs of nerve injury in all rats on 3 dPI. CM group showed faster recovery on 14 dPI compared with the ST group that only showed improvement after the 28th dPI. Electrophysiological images showed better electrical conduction in CM than ST group, while histological features showed higher S100 marker was expressed in CM compared with ST, as well as SH group on 7 and 70 dPI. Overall, UC-MSC CM affected peripheral nerve regeneration after 14 dPI.