Temple University School of Podiatric Medicine Journal Review Club

Editor's note: This post is part of the Temple University School of Podiatric Medicine (TUSPM) journal review club blog series. In each blog post, a TUSPM student will review a journal article relevant to wound management and related topics and provide their evaluation of the clinical research therein.

Article Title: IL-7 Over-expression Enhances Therapeutic Potential of Rat Bone Marrow Mesenchymal Stem Cells for Diabetic Wounds

Authors: Khalid, R. S., Khan, I., Zaidi, M. B., Naeem, N., Haneef, K., Qazi, R., Habib, R., Malick, T. S., Ali, A. and Salim, A.

Journal: Wound Rep Reg

Reviewed by: Zoha Khan, Class of 2020, Temple University School of Podiatric Medicine

Introduction

The therapeutic potential of stem cells in chronic, non-healing diabetic wounds comes from their ability to secrete cytokines which play a role in healing. A study with critical limb ischemia patients was done in the past where it was reported that using autologous mesenchymal stem cells (MSCs) could lower limb amputation rates. MSCs have been genetically modified with stromal cell-derived factor 1 (SDF-1) and vascular endothelial growth factor (VEGF) in the past to improve wound healing. This study evaluates the healing potential of chronic diabetic wounds with transfection of interleukin 7 (IL-7) into rat bone marrow MSCs.

Methods

In vitro method: IL-7 viral vector plasmid was delivered to PT67 packaging cell line which was transfected to rat bone marrow MSCs. Transfected and normal MSCs were grown and scratches were made using a 10 microliter pipette tip. Migration of cells and wound area closure was measured using Image J software. In vivo method: Streptozocin induced rate model of type 1 diabetes (blood sugar >300 mg/dL) was used. A single wound was created in both normal and diabetic animals by excising a full-thickness flap of skin (2cm). Normal and IL-7 transfected MSCs were transplanted in the respective treatment groups of diabetic wound models subcutaneously just outside the periphery of wound. Gene expression was measured in normal and diabetic wounds as well as in normal and IL-7 transfected BM-MSCs using the SV total RNA isolation kit.

Results

In the in vitro scratch test, the area of scratch was reduced after 24 hours and 48 hours in both normal and IL-7 transfected MSCs but area reduction was more pronounced in the latter. The number of cells migrating to close the area of scratch was also more in transfected MSCs compared to normal MSCs. In the in vivo test, measurement of wound area showed remarkably significant reduction in wound size in the case of the group transplanted with IL-7 transfected MSCs when compared with the diabetic control. Normal MSCs also showed enhanced reduction but less than that of IL-7 transfected MSCs. Histological analysis showed that the transfected group showed increased number of blood vessels as detected by the alpha SMA and CD31 staining as compared to normal MSCs and the diabetic control group.

Discussion

IL-7 was used in this study based on its role in cell survival, proliferation and differentiation processes. Through this study there was a noticeably increased rate of wound healing in the IL-7 transfected MSCs versus the normal MSCs in vitro. Reduction of scratch wound was due to the migration of these MSCs towards the injured area. This verifies that expression of IL-7 gene as well as induction of its downstream angiogenic genes (VEGF, HGF, FLT-1 and FLK-1) has conditioned the MSCs to become more effective for wound healing. The in vivo results were also consistent with the in vitro findings showing that IL-7 overexpression in MSCs not only enhanced angiogenesis but also increased rate of wound closure. The diabetic group with no cellular treatment had extremely poor vascular regeneration. In the group transplanted with normal MSCs there was moderate vascular restoration, but the group transplanted with IL-7 transfected MSCs showed enhanced regeneration of blood vessels (proven by the increase in the number of cells positive for alpha smooth muscle actin and CD31 ).

About the Author

Zoha Khan is a third year podiatric medical student at Temple University School of Podiatric Medicine (TUSPM) in Philadelphia, Pennsylvania. She graduated from the University of Maryland, College Park in 2016 with a Bachelor of Science in Physiology and Neurobiology. Zoha has been very active in research, interning at the Institute for Bioscience and Biotechnology Research (IBBR) and at multiple institutes at the National Institutes of Health including NIAID, NIMH, and NHLBI. During her time at the National Institutes of Health is where her interest in becoming a physician and eventually a podiatrist began. Dr. James McGuire is the director of the Leonard S. Abrams Center for Advanced Wound Healing and an associate professor of the Department of Podiatric Medicine and Orthopedics at the Temple University School of Podiatric Medicine in Philadelphia.