Modulation of p75NTR on Mesenchymal Stem Cells Increases Their Vascular Protection in Retinal Ischemia-Reperfusion Mouse Model

Abstract

Mesenchymal stem cells (MSCs) are a promising therapy to improve vascular repair, yet their role in ischemic retinopathy is not fully understood. The aim of this study is to investigate the impact of modulating the neurotrophin receptor; p75NTR on the vascular protection of MSCs in an acute model of retinal ischemia/reperfusion (I/R). Wild type (WT) and p75NTR-/- mice were subjected to I/R injury by increasing intra-ocular pressure to 120 mmHg for 45 min, followed by perfusion. Murine GFP-labeled MSCs (100,000 cells/eye) were injected intravitreally 2 days post-I/R and vascular homing was assessed 1 week later. Acellular capillaries were counted using trypsin digest 10-days post-I/R. In vitro, MSC-p75NTR was modulated either genetically using siRNA or pharmacologically using the p75NTR modulator; LM11A-31, and conditioned media were co-cultured with human retinal endothelial cells (HREs) to examine the angiogenic response. Finally, visual function in mice undergoing retinal I/R and receiving LM11A-31 was assessed by visual-clue water-maze test. I/R significantly increased the number of acellular capillaries (3.2-Fold) in WT retinas, which was partially ameliorated in p75NTR-/- retinas. GFP-MSCs were successfully incorporated and engrafted into retinal vasculature 1 week post injection and normalized the number of acellular capillaries in p75NTR-/- retinas, yet ischemic WT retinas maintained a 2-Fold increase. Silencing p75NTR on GFP-MSCs coincided with a higher number of cells homing to the ischemic WT retinal vasculature and normalized the number of acellular capillaries when compared to ischemic WT retinas receiving scrambled-GFP-MSCs. In vitro, silencing p75NTR-MSCs enhanced their secretome, as evidenced by significant increases in SDF-1, VEGF and NGF release in MSCs conditioned medium; improved paracrine angiogenic response in HREs, where HREs showed enhanced migration (1.4-Fold) and tube formation (2-Fold) compared to controls. In parallel, modulating MSCs-p75NTR using LM11A-31 resulted in a similar improvement in MSCs secretome and the enhanced paracrine angiogenic potential of HREs. Further, intervention with LM11A-31 significantly mitigated the decline in visual acuity post retinal I/R injury. In conclusion, p75NTR modulation can potentiate the therapeutic potential of MSCs to harness vascular repair in ischemic retinopathy diseases.

P75 neurotrophin receptor as a therapeutic target for drug development to treat neurological diseases

“…What is more, LM11A‐31 can also prevent and potentially reverse age‐associated basal forebrain cholinergic neurons (BFCNs) degeneration (Xie et al, 2019), improves erectile function in a mouse model of cavernous nerve injury (Yin et al, 2021); protects neurogenesis after traumatic brain injury (Shi et al, 2013) and spinal cord injury (Tep et al, 2013), and potentiates the therapeutic potential of HD and MSCs to harness vascular repair in ischaemic retinopathy diseases (Elshaer et al, 2021; Simmons et al, 2016); and ameliorates cisplatin‐induced experimental peripheral neuropathy (Friesland et al, 2014). The persistence of HIV in the CNS leads to cognitive deficits in more than half of people living with HIV.…”

Lost in Translation: Neurotrophins Biology and Function in the Neurovascular Unit

“…For instance, treating diabetic rats with quercetin caused a significant increase in the level of neurotrophic factors NGF and BDNF as compared with controls (Ola and others 2017). Interestingly, deletion or modulation of p75 NTR activity coincided with decreases in the level of proNGF and increases in NGF expression in the diabetic retina (Elshaer and others 2019; Mohamed and others 2017; Mysona and others 2013) or ischemic retinopathy models (Elshaer and others 2019; Elshaer and others 2021; Mohamed and others 2017; Shanab and others 2015). As depicted in Figure 3A, restoring or improving the balance of mature NGF to proNGF coincided with significant decreases in retina neuro- and microvascular degeneration, preventing retinal inflammation and pathological angiogenesis.…”

“…Our studies demonstrated the anti-inflammatory and neuro- and vascular protective effects of LM11A-31 in response to diabetes (Barcelona and others 2016; Elshaer and others 2019; Galan and others 2017; Mysona and others 2013). Furthermore, the impact of LM11A-31 was shown for the first time to improve the homing, proliferation, and angiogenic properties of mesenchymal stem cells in vivo and in vitro (see Figure 4; extracted from Elshaer and others 2021). Finally, intervention treatment with LM11A-31 postischemic insult exerted neuro- and vascular protective effects assessed by visual acuity in a mouse model of ischemic retina (Elshaer and others 2021).…”

“…Furthermore, the impact of LM11A-31 was shown for the first time to improve the homing, proliferation, and angiogenic properties of mesenchymal stem cells in vivo and in vitro (see Figure 4; extracted from Elshaer and others 2021). Finally, intervention treatment with LM11A-31 postischemic insult exerted neuro- and vascular protective effects assessed by visual acuity in a mouse model of ischemic retina (Elshaer and others 2021).…”

Modulation of Mesenchymal Stem Cells for Enhanced Therapeutic Utility in Ischemic Vascular Diseases

“…Overexpression of HO-1 in MSCs showed partial restoration and a lower rate of retinal thinning of the inner plexiform layer, inner nuclear layer, and the outer nuclear layer of the retina in the ischemic retina injury model in rats [ 76 ]. Several animal studies demonstrated that transplantation of MSCs can delay the progression of retinal neurodegeneration and preserve neural retinal function [ 77 , 78 ]; however, the vascular protection of MSCs transplanted in the ischemic retina has not been fully elucidated. Introduction of MSCs paired with eliminating the p75 NTR gene decreased acellular capillaries in the ischemia-reperfusion model compared to controls [ 79 ].…”