tudy are available from the corresponding author on reasonable request.

Authors\' contributions
=======================

CW wrote the manuscript and directed/performed the experiments. JC performed MSC culture and blood examination. KC, XM and MQ performed the animal experiments and the histological examination of the sciatic nerves. ZW and YW designed the experiments, revised and proved the manuscript. All authors read and approved the final manuscript.

Ethics approval and consent to participate
==========================================

The experiments comply with the current laws of the country in which they were performed. The present study was approved by the Institutional Animal Ethical Committee (Qingdao, China) and the Ethics Committee of the Affiliated Hospital of Qingdao University (Qingdao, China). Informed consent was obtained for the present study.

Patient consent for publication
===============================

The patient who donated her umbillical cord provided written informed consent for the publication of any associated data and accompanying images.

Competing interests
===================

The authors declare that they have no competing interests.

![Body weight, blood glucose, dosage of insulin and C-peptide were examined among the six experimental groups. Following the respective administration of therapies, the body weight of mice in the RSV, insulin and RSV+ MSCs groups was increased compared with the diabetic control group. Blood glucose in the MSCs and RSV+ MSCs groups was decreased compared with the diabetic control, insulin and RSV groups following therapy. Furthermore, glucose levels in the MSCs and RSV+ MSCs groups reached a normal level at day 14, which lasted until the end of the experiment. The blood glucose in the RSV group was lower compared with the diabetic control group, yet higher compared with the MSCs group and MSCs + RSV group. The dosage of insulin required in the MSCs group and RSV+ MSCs group was decreased compared with the insulin group and RSV group. Levels of C-