Paracrine Factors of Mesenchymal Stem Cells Recruit Macrophages and Endothelial Lineage Cells and Enhance Wound Healing

Abstract

Bone marrow derived mesenchymal stem cells (BM-MSCs) have been shown to enhance wound healing; however, the mechanisms involved are barely understood. In this study, we examined paracrine factors released by BM-MSCs and their effects on the cells participating in wound healing compared to those released by dermal fibroblasts. Analyses of BM-MSCs with Real-Time PCR and of BM-MSC-conditioned medium by antibody-based protein array and ELISA indicated that BM-MSCs secreted distinctively different cytokines and chemokines, such as greater amounts of VEGF-α, IGF-1, EGF, keratinocyte growth factor, angiopoietin-1, stromal derived factor-1, macrophage inflammatory protein-1alpha and beta and erythropoietin, compared to dermal fibroblasts. These molecules are known to be important in normal wound healing. BM-MSC-conditioned medium significantly enhanced migration of macrophages, keratinocytes and endothelial cells and proliferation of keratinocytes and endothelial cells compared to fibroblast-conditioned medium. Moreover, in a mouse model of excisional wound healing, where concentrated BM-MSC-conditioned medium was applied, accelerated wound healing occurred compared to administration of pre-conditioned or fibroblast-conditioned medium. Analysis of cell suspensions derived from the wound by FACS showed that wounds treated with BM-MSC-conditioned medium had increased proportions of CD4/80-postive macrophages and Flk-1-, CD34- or c-kit-positive endothelial (progenitor) cells compared to wounds treated with pre-conditioned medium or fibroblast-conditioned medium. Consistent with the above findings, immunohistochemical analysis of wound sections showed that wounds treated with BM-MSC-conditioned medium had increased abundance of macrophages. Our results suggest that factors released by BM-MSCs recruit macrophages and endothelial lineage cells into the wound thus enhancing wound healing.

Therapeutic Potential of Gingival Fibroblasts for Cutaneous Radiation Syndrome: Comparison to Bone Marrow-Mesenchymal Stem Cell Grafts

“…Although macrophages are the major source of proinflammatory cytokines, neither the CD68 mRNA level nor immunostaining showed a reduction in macrophage infiltration after either MSC or GF treatment. The possibility that treatment with bone marrow-derived MSCs enhances wound healing by increasing the recruitment of macrophages to the wound site has been evoked [37]. Recruited macrophages induce granulation tissue and myofibroblast differentiation during the early stage of the repair and are crucial for the stabilization of vascular structures and the transition of granulation tissue to scar tissue during intermediate stages of repair [28].…”

“…Although M2 macrophages provide a source for VEGF [28], analysis of the MSC-conditioned medium indicated that MSC secretes many tissue repair mediators, including angiogenic proteins such as VEGFs and epithelial cell stimulatory proteins such as EGF and FGF7 [37]. Physiological levels of these growth factors are critical for ensuring wound healing [40].…”

“…Using BM-MSC-derived conditioned medium previous report demonstrated that BM-MSC enhances wound healing through paracrine pathways and the growth factors and cytokines released together to modulate the local environment, affecting the proliferation, migration, differentiation, and functional recovery of resident cells [37]. The mechanism of GF therapeutic effect on wound healing such as MSC therapy involved inflammatory modulation associated to a switch of macrophages to an M2-like phenotype and an ECM remodeling is reinforced by previous observations where GF secretion factors inhibited dendritic cell differentiation [21].…”

Dehydrated human amnion/chorion membrane regulates stem cell activity in vitro

“…Stem cells including mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) are recruited to a healing wound, where they support healing in a variety of ways 3, 4, 5, 6. The healing potential of stem cells has resulted in the development of stem cell therapies for the treatment of chronic wounds.…”

14S,21R-dihydroxy-docosahexaenoic Acid Treatment Enhances Mesenchymal Stem Cell Amelioration of Renal Ischemia/Reperfusion Injury

“…MSCs generate an array of cytokines and growth factors [15,56] that protect kidneys from injuries [15][16][17]57]. Therefore, we postulated that 14S,21R-diHDHA treatment enhanced the beneficial effects of MSCs by augmenting their secretion of renotrophic factors.…”