Topical Application of Conditioned Medium from Hypoxically Cultured Amnion-Derived Mesenchymal Stem Cells Promotes Wound Healing in Diabetic Mice

Abstract

We read with great interest the article entitled “Topical Application of Conditioned Medium from Hypoxically Cultured Amnion-Derived Mesenchymal Stem Cells Promotes Wound Healing in Diabetic Mice,” by Takahashi et al.1 The authors performed an in vivo experiment to demonstrate that hypoxic conditioned medium from amnion-derived mesenchymal stem cells enhanced wound healing in a diabetic mouse model. This study brings new opportunities for the treatment of diabetic wounds. The authors prepared the diabetic mouse model by injecting streptozotocin, which induces acute diabetes. It is well known that diabetes is a multisystemic chronic disease, involving neurological and vascular lesions. The vasculopathy and neuropathy are closely associated with the pathophysiology of the diabetic wound.2 Thus, a disadvantage of using an acute diabetic model is that the translation of the findings to the human setting is uncertain and challenging. To assess the level of inflammation in the diabetic wound, the authors performed quantitative polymerase chain reaction analyses on the expression levels of inflammation-related genes. Due to the posttranscription modification, the data on the transcriptional level do not necessarily represent the translational level. Thus, we suggest performing a Western blot or enzyme-linked immunosorbent assay on the protein level to increase the translation of the results. In their study, the authors isolated mesenchymal stem cells from the amnion. The authors mentioned several advantages of the amnion, including abundant availability, less damage, and fewer ethical concerns. Amnion-derived mesenchymal stem cells enhance diabetic wound healing through the paracrine effect, similar to adipose-derived mesenchymal stem cells.3 Further comparative studies are warranted to confirm the efficacy and safety of the above two mesenchymal stem cells. The hypoxic conditioned medium was made by culturing with serum-free α-minimal essential medium for 48 hours under hypoxia. However, the authors did not detect the composition of the media to demonstrate differences after culturing at different oxygen concentrations. Further study is warranted and would benefit from the comparison on the effect of different culture times on the paracrine function. For the preparation of the medium gel, the conditioned medium was mixed with 7% carboxymethyl cellulose. We wonder if there is the same effect via simple continuous injection of the hypoxic conditioned medium around the wounds. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. No funding was received for this work. Ping Jiang, M.D.Ping Cao, M.D.Tianyou HospitalAffiliated to Wuhan University of Science and TechnologyWuhan, People’s Republic of China