Cornea-Derived Mesenchymal Stromal Cells Therapeutically Modulate Macrophage Immunophenotype and Angiogenic Function

Abstract

Macrophages are crucial drivers of inflammatory corneal neovascularization and thus are potential targets for immunomodulatory therapies. We hypothesized that therapeutic use of cornea-derived mesenchymal stromal cells (cMSCs) may alter the function of macrophages. We found that cMSCs can modulate the phenotype and angiogenic function of macrophages. In vitro, cMSCs induce apoptosis of macrophages while preferentially promoting a distinct CD14 CD16 CD163 CD206 immunophenotype that has significantly reduced angiogenic effects based on in vitro angiogenesis assays. In vivo, application of cMSCs to murine corneas after injury leads to reduced macrophage infiltration and higher expression of CD206 in macrophages. Macrophages cocultured ("educated") by cMSCs express significantly higher levels of anti-angiogenic and anti-inflammatory factors compared with control macrophages. In vivo, injured corneas treated with cMSC-educated macrophages demonstrate significantly less neovascularization compared with corneas treated with control macrophages. Knocking down the expression of pigment epithelial derived factor (PEDF) in cMSCs significantly abrogates its modulating effects on macrophages, as shown by the reduced rate of apoptosis, decreased expression of sFLT-1/PEDF, and increased expression of vascular endothelial growth factor-A in the cocultured macrophages. Similarly, cMSCs isolated from PEDF knockout mice are less effective compared with wild-type cMSCs at inhibiting macrophage infiltration when applied to wild-type corneas after injury. Overall, these results demonstrate that cMSCs therapeutically suppress the angiogenic capacity of macrophages and highlight the role of cMSC secreted PEDF in the modulation of macrophage phenotype and function. Stem Cells 2018;36:775-784.

Extracellular Vesicle-Educated Macrophages Promote Early Achilles Tendon Healing

“…To characterize the immune‐phenotype of EEMs compared with MQs, we examined the expression of CD206 and PD‐L1 of the two biologic CD14+ macrophage isolates used in this study. CD206, a mannose receptor, is a well‐known marker of M2 macrophages and our previously described MSC educated macrophages (MEMs); PD‐L1 an immune‐inhibitory checkpoint molecule . As shown in Figure B, C, CD206 and PD‐L1 were significantly higher in mean fluorescence intensity and percent cells from EEMs compared with the control MQs, indicating the MSC‐derived EVs were able to “educate” the macrophages to become more M2‐like.…”

“…Macrophage polarization, both in vitro and in vivo, can be induced by mesenchymal stromal/stem cell (MSC) paracrine activity . In mammalian models of ligament or tendon healing, MSC treatments increased the presence of endogenous M2 macrophages and associated anti‐inflammatory cytokines, which subsequently resulted in improved tendon and ligament healing .…”

Propranolol Attenuates Proangiogenic Activity of Mononuclear Phagocytes: Implication in Choroidal Neovascularization

“…Macrophages can produce diverse angiogenic factors, such as VEGF, PDGF, TGFb, FGF, [50][51][52] as well as antiangiogenic factors, including the potent PEDF and at times TSP-1. 17,18,53 PEDF directly targets PEDF-R-expressing endothelial cells to inhibit vasoproliferation and promote cell apoptosis. 23,37 In the eye, PEDF is located predominantly in RPE cells.…”

“…In this context, CNV as observed in various clinical conditions as well as in the laser-induced photocoagulation model, is associated with an inflammatory component. 14 Of relevance, mononuclear phagocytes (MPs) attracted to pathologic sites 15,16 are known to exert pro-and antiangiogenic effects, depending on their polarization resulting in the release of pro-and antiangiogenic factors inherently 17,18 or by stimulating the release of these factors from interacting cells, such as RPE. 14,19,20 However, whether modulation of relevant inflammation-associated CNV (including AMD, ocular histoplasmosis, Stargardt's disease, and degenerative myopia 21 ) by MPs depends in part upon their expression of b-adrenergic receptors, 22 has yet to be explored; moreover, the mechanism by which b-adrenoceptor inhibition in MPs could convey antiangiogenic properties to the choroid is also not known.…”

Fibrosis: Shared Lessons From the Lens and Cornea

“…A promising tool being investigated today is the use of mesenchymal stem cells (MSCs) or products derived from them to resolve existing fibrotic foci (Du et al, ; Liu et al, ; Coulson‐Thomas et al, ; Eslani et al, ). MSCs modulate the immune response when injected into injured tissues (Krampera et al, ; Bai et al, ; De Miguel et al, ).…”