Angiogenic properties of human placenta-derived adherent cells and efficacy in hindlimb ischemia

Stem Cell-Based Tissue Engineering Approaches for Diabetic Foot Ulcer: a Review from Mechanism to Clinical Trial

Diabetic foot ulcer (DFU) is a complication from incomplete or prolonged wound healing, at times requires amputation, putting substantial health and socioeconomic burden. Wound healing is a dynamic overlapping process that can be regulated by arrays of molecular factors showing redundancy in function. However, dysregulation in the mechanism of angiogenesis, extra cellular matrix (ECM) formation and immune modulation are the major causes for impair wound healing in hyperglycaemic patients. Despite development of wound care research, there is a lack of well-accepted targeted therapy with multidisciplinary approach for DFU treatment. Stem cell therapy holds a promising outcome both in preclinical and clinical trials because of its ability to promote healing via regeneration and specialized tissue differentiation. Among different types of stem cells, regenerative potential of mesenchymal stem cell (MSC) is well demonstrated in both experimental and clinical trial. Still there is a huge knowledge gap among medical practitioners for deciding the best stem cell source, administration route, and safety. This review strengthens the fact that why stem cell therapy is a promising candidate to treat DFU and cited multiple tissue engineering and biomaterial-based approaches for delivering stem cells and their aftermath paracrine events. Based on the pre-clinical and clinical studies, the review tried to come up with optimum stem cell source and delivery route for the treatment of DFU. At last, the review glances on possible direction to enhance therapeutics strategy for the same, including different approaches like: phytocompounds, exosomes, scaffold geometry, cell preconditioning and licensing etc.

Characterization of CRISPR/Cas9-edited human placental allogenic stromal cells with low tissue factor expression and reduced thrombotic effects

The tissue factor (TF/CD142) expressed by mesenchymal stromal cells (MSCs) has been regarded as a safety concern in clinical applications as it may trigger thrombosis when MSCs administered intravenously. Human placental allogenic stromal cells (ASCs) are culture-expanded, undifferentiated MSC-like cells derived from full-term postpartum placenta and possess immunomodulatory and pro-angiogenic activities, however, express TF. Here we performed CRISPR/Cas9-mediated TF gene knock out (TFKO) in ASCs, leading to significantly lower TF expression, activity and thrombotic effects. ASCs' characteristics including expansion, expression of phenotypic markers and secretory profile remained unchanged in edited cells, and their immunomodulatory activities, which are functionally relevant to therapeutic applications, were not affected upon TFKO. Taken together, this study provides a feasible strategy which could improve the clinical safety features of MSC-based cell therapy by CRISRP/Cas9-mediated TF gene knock out.

Differential Angiogenic Induction Impacts Nasal Polyp Tissue Growth

In chronic rhinosinusitis with nasal polyps, inflammatory edema drives tissue remodeling favoring anomalous growth of the nasal mucosa, but a proangiogenic contribution of nasal polyp in support of tissue growth is still controversial. The chorioallantoic membrane of chicken embryo model was employed to address the potentiality of nasal tissue fragments to modulate angiogenesis. Fifty-seven fertilized eggs were implanted with polyp or healthy nasal mucosa tissue or were kept as non-implanted controls. The embryos' size, length, and development stage, and chorioallantoic membrane vasculature morphology were evaluated after 48 h. Quantitative computer vision techniques applied to digital chorioallantoic membrane images automatically calculated the branching index as the ratio between the areas of the convex polygon surrounding the vascular tree and the vessels' area. Ethics approval and consent to participate: the study was approved by the Human Research Ethics Committee of the Federal University of São Paulo (CAAE number: 80763117.1.0000.5505) and by the Animal Research Ethics Committee of University of São Paulo (nº CEUA 602-2019). Mucosal, but not polyp tissue implants, hampered embryo development and induced underdeveloped chorioallantoic membranes with anastomosed, interrupted, and regressive vessels. Vessels' areas and branching indexes were higher among the chorioallantoic membranes with polyp implants and controls than among those with healthy mucosa implants. Nasal polyp presents differential angiogenic induction that impacts tissue growth.

Mesenchymal stem cell-based therapy for non-healing wounds due to chronic limb-threatening ischemia: A review of preclinical and clinical studies

Progressive peripheral arterial disease (PAD) can result in chronic limb-threatening ischemia (CLTI) characterized by clinical complications including rest pain, gangrene and tissue loss. These complications can propagate even more precipitously in the setting of common concomitant diseases in patients with CLTI such as diabetes mellitus (DM). CLTI ulcers are cutaneous, non-healing wounds that persist due to the reduced perfusion and dysfunctional neovascularization associated with severe PAD. Existing therapies for CLTI are primarily limited to anatomic revascularization and medical management of contributing factors such as atherosclerosis and glycemic control. However, many patients fail these treatment strategies and are considered "no-option," thereby requiring extremity amputation, particularly if non-healing wounds become infected or fulminant gangrene develops. Given the high economic burden imposed on patients, decreased quality of life, and poor survival of no-option CLTI patients, regenerative therapies aimed at neovascularization to improve wound healing and limb salvage hold significant promise. Cell-based therapy, specifically utilizing mesenchymal stem/stromal cells (MSCs), is one such regenerative strategy to stimulate therapeutic angiogenesis and tissue regeneration. Although previous reviews have focused primarily on revascularization outcomes after MSC treatments of CLTI with less attention given to their effects on wound healing, here we review advances in pre-clinical and clinical studies related to specific effects of MSC-based therapeutics upon ischemic non-healing wounds associated with CLTI.

PFKFB3-mediated glycometabolism reprogramming modulates endothelial differentiation and angiogenic capacity of placenta-derived mesenchymal stem cells

BACKGROUND

Mesenchymal stem cells (MSCs) have a great potential ability for endothelial differentiation, contributing to an effective means of therapeutic angiogenesis. Placenta-derived mesenchymal stem cells (PMSCs) have gradually attracted attention, while the endothelial differentiation has not been fully evaluated in PMSCs. Metabolism homeostasis plays an important role in stem cell differentiation, but less is known about the glycometabolic reprogramming during the PMSCs endothelial differentiation. Hence, it is critical to investigate the potential role of glycometabolism reprogramming in mediating PMSCs endothelial differentiation.

METHODS

Dil-Ac-LDL uptake assay, flow cytometry, and immunofluorescence were all to verify the endothelial differentiation in PMSCs. Seahorse XF Extracellular Flux Analyzers, Mito-tracker red staining, Mitochondrial membrane potential (MMP), lactate secretion assay, and transcriptome approach were to assess the variation of mitochondrial respiration and glycolysis during the PMSCs endothelial differentiation. Glycolysis enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) was considered a potential modulator for endothelial differentiation in PMSCs by small interfering RNA. Furthermore, transwell, in vitro Matrigel tube formation, and in vivo Matrigel plug assays were performed to evaluate the effect of PFKFB3-induced glycolysis on angiogenic capacities in this process.

RESULTS

PMSCs possessed the superior potential of endothelial differentiation, in which the glycometabolic preference for glycolysis was confirmed. Moreover, PFKFB3-induced glycometabolism reprogramming could modulate the endothelial differentiation and angiogenic abilities of PMSCs.

CONCLUSIONS

Our results revealed that PFKFB3-mediated glycolysis is important for endothelial differentiation and angiogenesis in PMSCs. Our understanding of cellular glycometabolism and its regulatory effects on endothelial differentiation may propose and improve PMSCs as a putative strategy for clinical therapeutic angiogenesis.

Experimental study of the antiulcer effect of cryopreserved placenta extract on a model of acetylsalicylic acid-induced ulcerogenesis

Introduction. The gastrotoxicity of nonsteroidal anti-inflammatory drugs is a leading side effect that significantly limits their clinical use, among other types of their toxicity (nephrotoxicity, hepatotoxicity, cardiotoxicity, etc.). Cryopreserved placenta extract has drawn our attention as a potential modifier of the ulcerogenic action of nonsteroidal anti-inflammatory drugs.

Aim. To characterize the cytoprotective properties of cryopreserved placenta extract by the condition of the mucous membrane of the proximal (esophagus and stomach) and distal (small and large intestine) parts of the gastrointestinal (GI) tract on the model of ASA-induced ulcerogenesis.

Material and methods. The study was performed using 28 male rats weighing 200-220 g. Subchronic ASA-induced ulcerogenesis of the digestive tract was reproduced by intragastrically administration to rats of ASA in a dose of 150 mg/kg. The effect of the studied drugs on the condition of the mucous membrane of the digestive tract was assessed macroscopically by the following criteria: edema, redness and hemorrhage on the surface of the mucous membrane. The ulcer index for each group of animals was calculated.

Results and discussion. Five doses of ASA 150 mg/kg cause damage to the esophagus, stomach, small and large intestines in all of the rats. The use of the proton pump inhibitor esomeprazole has pronounced gastrocytoprotective properties, but does not affect the ulcerogenic effect in the small intestine, and in the colon, it enhances it. This is indicated by ulcerative lesions of the colon in 57.1% of all rats administered ASA and esomeprazole, as well as in the folding of the gastric mucosa. In contrast, mild hyperemia of the gastric mucosa was seen in 28.6% of all rats and moderate hemorrhage in 57.1% of all rats due to the combined use of ASA and cryoextract placenta.

Conclusions. The use of cryopreserved placenta extract is statistically significantly (p <0.05) inferior to the antiulcer activity of esomeprazole in the stomach. Thus, the ulcer index on the background of the use of ASA and cryopreserved placenta extract was 0.97, and on the background of the use of ASA and esomeprazole – 0.39. In the distal parts of the GI tract cryoextract placenta showed cytoprotective properties against the background of induced ASA ulcerogenesis, in contrast to esomeprazole.

Innovative Cell and Platelet Rich Plasma Therapies for Diabetic Foot Ulcer Treatment: The Allogeneic Approach

Cutaneous chronic wounds are a major global health burden in continuous growth, because of population aging and the higher incidence of chronic diseases, such as diabetes. Different treatments have been proposed: biological, surgical, and physical. However, most of these treatments are palliative and none of them can be considered fully satisfactory. During a spontaneous wound healing, endogenous regeneration mechanisms and resident cell activity are triggered by the released platelet content. Activated stem and progenitor cells are key factors for ulcer healing, and they can be either recruited to the wound site from the tissue itself (resident cells) or from elsewhere. Transplant of skin substitutes, and of stem cells derived from tissues such as bone marrow or adipose tissue, together with platelet-rich plasma (PRP) treatments have been proposed as therapeutic options, and they represent the today most promising tools to promote ulcer healing in diabetes. Although stem cells can directly participate to skin repair, they primarily contribute to the tissue remodeling by releasing biomolecules and microvesicles able to stimulate the endogenous regeneration mechanisms. Stem cells and PRP can be obtained from patients as autologous preparations. However, in the diabetic condition, poor cell number, reduced cell activity or impaired PRP efficacy may limit their use. Administration of allogeneic preparations from healthy and/or younger donors is regarded with increasing interest to overcome such limitation. This review summarizes the results obtained when these innovative treatments were adopted in preclinical animal models of diabetes and in diabetic patients, with a focus on allogeneic preparations.

Exosomes Immunity Strategy: A Novel Approach for Ameliorating Intervertebral Disc Degeneration

Low back pain (LBP), which is one of the most severe medical and social problems globally, has affected nearly 80% of the population worldwide, and intervertebral disc degeneration (IDD) is a common musculoskeletal disorder that happens to be the primary trigger of LBP. The pathology of IDD is based on the impaired homeostasis of catabolism and anabolism in the extracellular matrix (ECM), uncontrolled activation of immunologic cascades, dysfunction, and loss of nucleus pulposus (NP) cells in addition to dynamic cellular and biochemical alterations in the microenvironment of intervertebral disc (IVD). Currently, the main therapeutic approach regarding IDD is surgical intervention, but it could not considerably cure IDD. Exosomes, extracellular vesicles with a diameter of 30–150 nm, are secreted by various kinds of cell types like stem cells, tumor cells, immune cells, and endothelial cells; the lipid bilayer of the exosomes protects them from ribonuclease degradation and helps improve their biological efficiency in recipient cells. Increasing lines of evidence have reported the promising applications of exosomes in immunological diseases, and regarded exosomes as a potential therapeutic source for IDD. This review focuses on clarifying novel therapies based on exosomes derived from different cell sources and the essential roles of exosomes in regulating IDD, especially the immunologic strategy.

Placenta derived Mesenchymal Stem Cells transplantation in Type 1 diabetes: preliminary report of phase 1 clinical trial

Introduction

Type 1 Diabetes Mellitus (T1DM) is an auto immune reaction against insulin secreting beta cells. Exogenous insulin administration is the only standard treatment for T1DM. However, despite tight glycemic control many patients will develop chronic life-threatening complications. Recently, stem cell transplantation has been suggested as a novel treatment for eliminating the beta cell damage and promoting their regeneration by modulating auto-immunity. To our knowledge; this is the first preliminary report of placenta derived MSCs (PLMSCs) transplantation in juvenile T1DM.

Method

An Open label non-randomized phase 1 clinical trial was designed to evaluate the safety of PLMSCs transplantation in new onset juvenile T1DM (IRCT20171021036903N2). PLMSCs were manufactured in our clean room facility using a Xeno-free/GMP compliant protocol. The first series of patients (n = 4) received one dose of1 × 10⁶ PLMSCs/kg intravenously. Diabetic clinical and laboratory parameters and side effects were evaluated weekly for the first month, monthly for 6 months, and then every 3 month till 1 year.

Results

Serious adverse events were not seen during 1 year follow-up. Partial remission and hypoglycemic attacks were happened one month after transplantation in two patients. ZnT8-Ab decreased till month 3 and then increased again in all patients. Anti Gad-Ab decreased till month 3 of follow up then increased.

Discussion

This preliminary report of our phase I clinical trial demonstrated the short term safety of PLMSCs transplantation in juvenile T1DM. To prove the long term safety and probable efficacy of this treatment more investigations are needed.

Trial registration

Iranian Registry of Clinical Trials: IRCT20171021036903N2.

Phase 2a randomized controlled study investigating the safety and efficacy of PDA-002 in diabetic peripheral neuropathy

Neuropathy is a major cause of morbidity and mortality in individuals with diabetes, with no effective therapy to alter the inevitable progression of nerve damage. We hypothesized that mesenchymal stroma cell-like populations, that are characterized as immune modulators also have the potential of inducing angiogenesis and neurite outgrowth, might be useful in treating diabetic peripheral neuropathy (DPN). The aims of this study were to investigate the efficacy and safety of mesenchymal stem cell-like product (PDA-002) in treating DPN. A phase-2 randomized placebo-controlled trial was conducted in 26 patients with DPN. Treatment consisted of three rounds of intramuscular injections in one lower limb using one of the three randomized treatment arms PDA-002 (low-dose 3 × 10⁶ cells), PDA-002 (high-dose 30 × 10⁶ cells), or placebo. Three treatments per patient occurred on days 1, 29, and 57. Study endpoints included efficacy and safety of PDA-002 in treating DPN in both lower extremities following unilateral local injection. Outcome measures included intra-epidermal nerve fiber density (IENFD) up to 1 year from the day of treatment with 6-month as the primary outcome measurement. In this phase 2 study of DPN, PDA-002 was well tolerated in both doses. No significant changes were noted in IENFD in both the treated and untreated leg in the NIS-LL, NTSS-6, or UENS. Mesenchymal stem cells represent a novel mechanism for treating diabetic neuropathy and are well tolerated. Preliminary results highlight the need of further investigation of PDA-001 as a disease modifying agent for treatment of DPN.

Gut flora-targeted photobiomodulation therapy improves senile dementia in an Aß-induced Alzheimer's disease animal model

BACKGROUND

Emerging evidence suggests that the gut microbiota plays an important role in the pathological progression of Alzheimer's disease (AD). Photobiomodulation (PBM) therapy is believed to have a positive regulatory effect on the imbalance of certain body functions, including inflammation, immunity, wound healing, nerve repair, and pain. Previous studies have found that the intestinal flora of patients with AD is in an unbalanced state. Therefore, we have proposed the use of gut flora-targeted PBM (gf-targeted PBM) as a method to improve AD in an Aß-induced AD mouse model.

METHODS

PBM was performed on the abdomen of the mice at the wavelengths of 630 nm, 730 nm, and 850 nm at 100 J/cm2 for 8 weeks. Morris water maze test, immunofluorescence and proteomic of hippocampus, and intestinal flora detection of fecal were used to evaluate the treatment effects of gf-targeted PBM on AD rats.

RESULTS

PBM at all three wavelengths (especially 630 nm and 730 nm) significantly improved learning retention as measured by the Morris water maze. In addition, we found reduced amyloidosis and tau phosphorylation in the hippocampus by immunofluorescence in AD mice. By using a quantitative proteomic analysis of the hippocampus, we found that gf-targeted PBM significantly altered the expression levels of 509 proteins (the same differentially expressed proteins in all three wavelengths of PBM), which involved the pathways of hormone synthesis, phagocytosis, and metabolism. The 16 s rRNA gene sequencing of fecal contents showed that PBM significantly altered the diversity and abundance of intestinal flora. Specifically, PBM treatment reversed the typical increase of Helicobacter and uncultured Bacteroidales and the decrease of Rikenella seen in AD mice.

CONCLUSIONS

Our data indicate that gf-targeted PBM regulates the diversity of intestinal flora, which may improve damage caused by AD. Gf-targeted PBM has the potential to be a noninvasive microflora regulation method for AD patients.

Conditioned medium from primary cytotrophoblasts, primary placenta-derived mesenchymal stem cells, or sub-cultured placental tissue promoted HUVEC angiogenesis in vitro

Background

As a large capillary network, the human placenta plays an important role throughout pregnancy. Placental vascular development is complex and delicate and involves many types of placental cells, such as trophoblasts, and mesenchymal stem cells. There has been no systematic, comparative study on the roles of these two groups of placental cells and the whole placental tissue in the placental angiogenesis. In this study, primary cytotrophoblasts (CTBs) from early pregnancy and primary human placenta-derived mesenchymal stem cells (hPDMSCs) from different stages of pregnancy were selected as the cell research objects, and full-term placental tissue was selected as the tissue research object to detect the effects of their conditioned medium (CM) on human umbilical vein endothelial cell (HUVEC) angiogenesis.

Methods

We successfully isolated primary hPDMSCs and CTBs, collected CM from these placental cells and sub-cultured placental tissue, and then evaluated the effects of the CM on a series of angiogenic processes in HUVECs in vitro. Furthermore, we measured the levels of angiogenic factors in the CM of placental cells or tissue by an angiogenesis antibody array.

Results

The results showed that not only placental cells but also sub-cultured placental tissue, to some extent, promoted HUVEC angiogenesis in vitro by promoting proliferation, adhesion, migration, invasion, and tube formation. We also found that primary placental cells in early pregnancy, whether CTBs or hPDMSCs, played more significant roles than those in full-term pregnancy. Placental cell-derived CM collected at 24 h or 48 h had the best effect, and sub-cultured placental tissue-derived CM collected at 7 days had the best effect among all the different time points. The semiquantitative angiogenesis antibody array showed that 18 of the 43 angiogenic factors had obvious spots in placental cell-derived CM or sub-cultured placental tissue-derived CM, and the levels of 5 factors (including CXCL-5, GRO, IL-6, IL-8, and MCP-1) were the highest in sub-cultured placental tissue-derived CM.

Conclusions

CM obtained from placental cells (primary CTBs or hPDMSCs) or sub-cultured placental tissue contained proangiogenic factors and promoted HUVEC angiogenesis in vitro. Therefore, our research is helpful to better understand placental angiogenesis regulation and provides theoretical support for the clinical application of placental components, especially sub-cultured placental tissue-derived CM, in vascular tissue engineering and clinical treatments.

Human mesenchymal stromal/stem cells recruit resident pericytes and induce blood vessels maturation to repair experimental spinal cord injury in rats

Angiogenesis is considered to mediate the beneficial effects of mesenchymal cell therapy in spinal cord injury. After a moderate balloon-compression injury in rats, injections of either human adipose tissue-derived stromal/stem cells (hADSCs) or their conditioned culture media (CM-hADSC) elicited angiogenesis around the lesion site. Both therapies increased vascular density, but the presence of hADSCs in the tissue was required for the full maturation of new blood vessels. Only animals that received hADSC significantly improved their open field locomotion, assessed by the BBB score. Animals that received CM-hADSC only, presented haemorrhagic areas and lack pericytes. Proteomic analyses of human angiogenesis-related factors produced by hADSCs showed that both pro- and anti-angiogenic factors were produced by hADSCs in vitro, but only those related to vessel maturation were detectable in vivo. hADSCs produced PDGF-AA only after insertion into the injured spinal cord. hADSCs attracted resident pericytes expressing NG2, α-SMA, PDGF-Rβ and nestin to the lesion, potentially contributing to blood vessel maturation. We conclude that the presence of hADSCs in the injured spinal cord is essential for tissue repair.

Mesenchymal Stem Cells Decrease M1/M2 Ratio and Alleviate Inflammation to Improve Limb Ischemia in Mice

BACKGROUND Limb ischemia (LI) is the underlying pathology of peripheral artery disease (PAD). Macrophages play a critical role in inflammation and can contribute to the exacerbation or reduction of inflammation. Transplantation of mesenchymal stem cells (MSCs) is an emerging therapeutic strategy for PAD. However, the mechanism by which human placenta-derived mesenchymal stem cells (PMSCs) regulate macrophage differentiation in ischemic tissue remains unclear. MATERIAL AND METHODS Placentas were obtained from healthy donors with normal 38- to 40-week gestation, and PMSCs were isolated from the placentas and cultured. A mouse model of hind-limb ischemia was established. Ischemic limbs were injected intramuscularly with about 5×10⁶ PMSCs in the PMSCs group or a placebo solution (phosphate-buffered saline) in the control group at 4 different sites 1 day after the procedure. The blood perfusion of hind-limbs and the histological morphology were observed at day 1, 7, and 14 after the surgical procedure. Macrophages were detected by flow cytometry. The expression of serum tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, and IL-10 were detected by enzyme-linked immunosorbent assay (ELISA). The expression of CD31 and smooth muscle alpha-actin (alpha-SMA) in frozen muscle samples were detected by immunofluorescence staining. RESULTS In the PMSCs group, blood perfusion was gradually recovered and ischemic injury was markedly alleviated. The percentage of M2-like macrophages was increased dramatically, while the M1/M2 macrophage ratio was reduced. The expression of TNF-alpha and IL-6 was reduced, while the IL-10 level was elevated. The expression and density of CD31- and alpha-SMA-positive vessels were both significantly increased. CONCLUSIONS Transplanted PMSCs alleviated inflammation, promoted neovascularization, and improved hind limb ischemia through regulating macrophage differentiation toward the M2 phenotype and cytokine secretion. Cytokine manipulation of macrophage phenotypes may have potential therapeutic benefits in injured ischemic limbs.

Placental mesenchymal stromal cells as an alternative tool for therapeutic angiogenesis

Dysregulation of angiogenesis is a phenomenon observed in several disorders such as diabetic foot, critical limb ischemia and myocardial infarction. Mesenchymal stromal cells (MSCs) possess angiogenic potential and have recently emerged as a powerful tool for cell therapy to promote angiogenesis. Although bone marrow-derived MSCs are the primary cell of choice, obtaining them has become a challenge. The placenta has become a popular alternative as it is a highly vascular organ, easily available and ethically more favorable with a rich supply of MSCs. Comparatively, placenta-derived MSCs (PMSCs) are clinically promising due to their proliferative, migratory, clonogenic and immunomodulatory properties. PMSCs release a plethora of cytokines and chemokines key to angiogenic signaling and facilitate the possibility of delivering PMSC-derived exosomes as a targeted therapy to promote angiogenesis. However, there still remains the challenge of heterogeneity in the isolated populations, questions on the maternal or fetal origin of these cells and the diversity in previously reported isolation and culture conditions. Nonetheless, the growing rate of clinical trials using PMSCs clearly indicates a shift in favor of PMSCs. The overall aim of the review is to highlight the importance of this rather poorly understood cell type and emphasize the need for further investigations into their angiogenic potential as an alternative source for therapeutic angiogenesis.

Concise Review: Skeletal Muscle as a Delivery Route for Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) have demonstrated extensive capacity to modulate a catabolic microenvironment toward tissue repair. The fate, biodistribution, and dwell time of the in vivo delivered MSCs largely depend on the choice of the cell delivery route. Intramuscular (IM) delivery of MSCs is clinically safe and has been used for the effective treatment of local pathologies. Recent findings have shown that the secretome of the IM‐delivered MSCs enters the circulation and provides systemic effects on distant organs. In addition, muscle tissue provides a safe residence for the delivered MSCs and an extended secretorily active dwell time compared with other delivery routes. There are, however, controversies concerning the fate of MSCs post IM‐delivery and, specifically, into an injured site with proinflammatory cues. This review seeks to provide a brief overview of the fate and efficacy of IM‐delivered MSCs and to identify the gaps that require further assessment for adoption of this promising route in the treatment of systemic disease. stem cells translational medicine2019;8:456–465

Advances in perinatal stem cells research: a precious cell source for clinical applications

Perinatal tissues possess numerous types of stem (stromal) cells, which are considered effective candidates for cell therapy. These tissues possess common characteristics of both embryonic and adult stem cells, and cell therapists have begun to use perinatal stem cells to treat several diseases. Despite their benefits, these cells are considered biological waste and usually discarded after delivery. This review highlights the characteristics and potential clinical applications in regenerative medicine of perinatal stem cell sources - cord blood hematopoietic stem cells, umbilical cord mesenchymal stem cells, amniotic membrane stem cells, amniotic fluid stem cells, amniotic epithelial cells and chorionic mesenchymal stem cells.

Placenta-derived PLX-PAD mesenchymal-like stromal cells are efficacious in rescuing blood flow in hind limb ischemia mouse model by a dose- and site-dependent mechanism of action

BACKGROUND

In peripheral artery disease (PAD), blockage of the blood supply to the limbs, most frequently the legs, leads to impaired blood flow and tissue ischemia. Pluristem's PLX-PAD cells are placenta-derived mesenchymal stromal-like cells currently in clinical trials for the treatment of peripheral artery diseases.

METHODS

In this work, the hind limb ischemia (HLI) mouse model was utilized to study the efficacy and mechanism of action of PLX-PAD cells. ELISA assays were performed to characterize and quantitate PLX-PAD secretions in vitro.

RESULTS

PLX-PAD cells administered intramuscularly rescued blood flow to the lower limb after HLI induction in a dose-dependent manner. While rescue of blood flow was site-dependent, numerous administration regimes enabled rescue of blood flow, indicating a systemic effect mediated by PLX-PAD secretions. Live PLX-PAD cells were more efficacious than cell lysate in rescuing blood flow, indicating the importance of prolonged cytokine secretion for maximal blood flow recovery. In vitro studies showed a multifactorial secretion profile including numerous pro-angiogenic proteins; these are likely involved in the PLX-PAD mechanism of action.

DISCUSSION

Live PLX-PAD cells were efficacious in rescuing blood flow after the induction of HLI in the mouse model in a dose- and site-dependent manner. The fact that various administration routes of PLX-PAD rescued blood flow indicates that the mechanism of action likely involves one of systemic secretions which promote angiogenesis. Taken together, the data support the further clinical testing of PLX-PAD cells for PAD indications.

Safety and efficacy of intramuscular human placenta-derived mesenchymal stromal-like cells (cenplacel [PDA-002]) in patients who have a diabetic foot ulcer with peripheral arterial disease

The objective of this study was to examine the safety of cenplacel (PDA‐002) in patients with peripheral arterial disease (PAD) and a diabetic foot ulcer (DFU). Cenplacel is a mesenchymal‐like cell population derived from full‐term human placenta. This phase 1, dose‐escalation study investigated cenplacel in diabetic patients with chronic DFUs (Wagner grade 1 or grade 2) and PAD [ankle‐brachial index (ABI) >0·5 and ≤0·9], enrolled sequentially into each of four dose cohorts (3 × 10⁶, 10 × 10⁶, 30 × 10⁶ and 100 × 10⁶ cells; administered intramuscularly on study days 1 and 8 in combination with standard of care). Overall, cenplacel was well tolerated in all 15 patients in the study. Before enrollment, nine patients had an ulcer for ≥6 months and 11 had an ABI of 0·7–0·85. No patient met dose‐limiting toxicity criteria and no treatment‐related serious adverse events were reported. There was preliminary evidence of ulcer healing in seven patients (five complete; two partial) within 3 months of cenplacel treatment, and circulating endothelial cell levels (a biomarker of vascular injury in PAD) were decreased within 1 month. Cenplacel was generally safe and well tolerated in patients with chronic DFUs and PAD. Outcomes from this study informed the doses, endpoints, biomarkers and patient population for an ongoing phase 2 trial.