Objectives: We have previously shown that stromal cell–derived factor-1α (SDF-1α) is downregulated within diabetic cutaneous wounds, and that direct application of recombinant SDF-1α increases wound closure rates, neovascularization, and endothelial progenitor cell (EPC) recruitment. However, increased wound levels of exogenous SDF-1α results in elevated systemic levels of this proangiogenic chemokine that raises concerns for tumorigenesis and inflammation. We now seek to test the efficacy of a novel, safer cell-based therapy (CBT) employing ex vivo primed bone marrow-derived stem cells (BMDSC) with SDF-1α. We also elucidate the mechanism of action of this new approach for accelerating diabetic wound healing.
Methods: Unfractionated BMDSC from diabetic Leprdb/db mice were incubated for 20 hours with SDF-1α (100 ng/mL) or bovine serum albumin (control). Pretreated BMDSC (1 × 106) were injected subcutaneously into full-thickness skin wounds in Leprdb/db mice (n = 8 per group). Wound closure rates, capillary density, and the recruitment of EPC were assessed with serial photography, DiI perfusion, confocal microscopy, and immunohistochemistry. The expression of molecular targets, which may mediate prohealing/proangiogenic effects of SDF-1α–primed BMDSC was evaluated by polymerase chain reaction array and immunoblotting assay. The biological function of a potential mediator was tested in a mouse wound-healing model. Serum SDF-1α levels were measured with enzyme-linked immunosorbent assay (ELISA).
Results: SDF-1α–primed BMDSC significantly promote wound healing (P < 0.0001), neovascularization (P = 0.0028), and EPC recruitment (P = 0.0059). Gene/protein expression studies demonstrate upregulation of Ephrin Receptor B4 and plasminogen as downstream targets potentially mediating the prohealing and proangiogenic responses. Ex vivo BMDSC activation and the subsequent inoculation of cells into wounds does not increase systemic SDF-1α levels.
Conclusions: We report a novel CBT that is highly effective in promoting healing and neovascularization in a murine model of type 2 diabetes. Furthermore, we identify new molecular targets that may be important for advancing the field of wound healing.
Stromal cell–derived factor-1α (SDF-1α) promotes diabetic wound healing, yet systemic administration (of this potent proangiogenic factor) brings about concerns of tumorigenesis and inflammation. We develop a novel, safer cell-based therapy employing ex vivo primed autologous bone marrow stem cells with SDF-1α and subsequent inoculation of primed cells into diabetic wounds for effective healing.
*Department of Surgery, Miller School of Medicine
†Sylvester Comprehensive Cancer Center, University of Miami, FL.
Reprints: Omaida C. Velazquez, MD, FACS, Division of Vascular and Endovascular Surgery, Room 3016, Holtz Center—JMH East Tower, 1611 NW 12th Avenue, Miami, FL 33136. E-mail: email@example.com.
Disclosure: This work is preclinical research on the efficacy and mechanism of action of an autologous cell-based therapy for diabetic wound healing utilizing stromal cell–derived factor-1α to prime diabetic unfractionated bone marrow stem cells ex vivo. This study has been supported by grants from the National Institutes of Health (R01DK-071084 & R01GM081570), and a grant from the Wallace H. Coulter Center for Translational Research, University of Miami. Equipment used in this study belongs to the Surgery Department, and core facilities of University of Miami, Miller School of Medicine.
No pharmaceutical medications were used in this study.