Stem cell mobilization with plerixafor and healing of diabetic ischemic wounds: A phase IIa, randomized, double-blind, placebo-controlled trial

Mechanism underlying the involvement of CXCR4/CXCL12 in diabetic wound healing and prospects for responsive hydrogel-loaded CXCR4 formulations

Diabetes mellitus is a prevalent chronic disease, often leading to complications, with chronic wounds being among the most challenging. Impairment of the CXCR4/CXCL12 signaling pathway, which plays a key role in cell mobilization, migration, and angiogenesis, significantly hampers the wound healing process in diabetic patients. Modulation of this pathway using CXCR4-targeted agents has shown promise in restoring wound repair capabilities. Additionally, the development of responsive hydrogels capable of adapting to external stimuli offers a powerful platform for drug delivery in chronic wound management. These hydrogels, when loaded with CXCR4 agonists or antagonists, enable controlled drug release and real-time therapeutic modulation. Integrating such hydrogels with existing wound healing strategies may provide an innovative and effective solution for overcoming the challenges associated with diabetic wound treatment.

Advancements in utilizing CD34+ stem cells for repairing diabetic vascular damage

Diabetes-related vascular damage is a frequent complication of diabetes that results in structural and functional impairment of blood vessels. This damage significantly heightens the risk of cardiovascular events. CD34+ stem cells have shown great potential in the treatment of diabetes-related vascular damage due to their differentiation and vascular repair capabilities. This article provides a review of the research hotspots on the role and mechanisms of CD34+ stem cells in the repair of diabetes-related vascular damage, including changes in cell quantity and function during diabetes, as well as the latest research on activating, protecting, or repairing these cells to prevent or treat vascular damage. The article also summarizes the impact of diabetes on the mobilization and function of CD34+ stem cells, emphasizing how diabetes negatively affects their ability to promote angiogenesis. These deficits can result in various complications, including issues with small blood vessels, coronary heart disease, foot problems, and retinal complications. On the clinical side, the article highlights the positive effects of CD34+ stem cell therapy in improving vascular function and tissue repair in diabetic patients, while also mentioning the inconsistencies in results between diabetes models and clinical studies, which necessitate further research to optimize treatment strategies. It emphasizes the importance of enhancing the mobilization, homing, and repair capabilities of CD34+ stem cells, as well as combining them with other treatment methods, to develop more effective strategies for treating diabetes-related vascular damage.

Angiogenesis during diabetic wound repair: from mechanism to therapy opportunity

Diabetes mellitus, a pervasive chronic metabolic disorder, is often associated with complications such as impaired wound healing. Various factors, most notably vascular deficiency, govern the wound repair process in diabetic patients, significantly impeding diabetic wound healing; therefore, angiogenesis and its role in diabetic wound repair have emerged as important areas of research. This review aims to delve into the mechanisms of angiogenesis, the effects of diabetes on angiogenesis, and the association between angiogenesis and diabetic wound repair. This will ultimately offer valuable guidance regarding the ideal timing of diabetic wound treatment in a clinical setting.

Sclerostin antibody corrects periodontal disease in type 2 diabetic mice

Type 2 diabetes (T2D) is on the rise worldwide and is associated with various complications in the oral cavity. Using an adult-onset diabetes preclinical model, we demonstrated profound periodontal alterations in T2D mice, including inflamed gingiva, disintegrated periodontal ligaments (PDLs), marked alveolar bone loss, and unbalanced bone remodeling due to decreased formation and increased resorption. Notably, we observed elevated levels of the Wnt signaling inhibitor sclerostin in the alveolar bone of T2D mice. Motivated by these findings, we investigated whether a sclerostin-neutralizing antibody (Scl-Ab) could rescue the compromised periodontium in T2D mice. Administering Scl-Ab subcutaneously once a week for 4 weeks, starting 4 weeks after T2D induction, led to substantial increases in bone mass. This effect was attributed to the inhibition of osteoclasts and promotion of osteoblasts in both control and T2D mice, effectively reversing the bone loss caused by T2D. Furthermore, Scl-Ab stimulated PDL cell proliferation, partially restored the PDL fibers, and mitigated inflammation in the periodontium. Our study thus established a T2D-induced periodontitis mouse model characterized by inflammation and tissue degeneration. Scl-Ab emerged as a promising intervention to counteract the detrimental effects of T2D on the periodontium, exhibiting limited side effects on other craniofacial hard tissues.

Plerixafor for pathogen-agnostic treatment in murine thigh infection and zebrafish sepsis

Plerixafor is a CXCR4 antagonist approved in 2008 by the FDA for hematopoietic stem cell collection. Subsequently, plerixafor has shown promise as a potential pathogen-agnostic immunomodulator in a variety of preclinical animal models. Additionally, investigator-led studies demonstrated plerixafor prevents viral and bacterial infections in patients with WHIM syndrome, a rare immunodeficiency with aberrant CXCR4 signaling. Here, we investigated whether plerixafor could be repurposed to treat sepsis or severe wound infections, either alone or as an adjunct therapy. In a Pseudomonas aeruginosa lipopolysaccharide (LPS)-induced zebrafish sepsis model, plerixafor reduced sepsis mortality and morbidity assessed by tail edema. There was a U-shaped response curve with the greatest effect seen at 0.1 μM concentration. We used Acinetobacter baumannii infection in a neutropenic murine thigh infection model. Plerixafor did not show reduced bacterial growth at 24 h in the mouse thigh model, nor did it amplify the effects of a rifampin antibiotic therapy, in varying regimens. While plerixafor did not mitigate or treat bacterial wound infections in mice, it did reduce sepsis mortality in zebra fish. The observed mortality reduction in our LPS model of zebrafish was consistent with prior research demonstrating a mortality benefit in a murine model of sepsis. However, based on our results, plerixafor is unlikely to be successful as an adjunct therapy for wound infections. Further research is needed to better define the scope of plerixafor as a pathogen-agnostic therapy. Future directions may include the use of longer acting CXCR4 antagonists, biased CXCR4 signaling, and optimization of animal models.

The Efficacy of Stem Cells in Wound Healing: A Systematic Review

Wound healing is an intricate process involving coordinated interactions among inflammatory cells, skin fibroblasts, keratinocytes, and endothelial cells. Successful tissue repair hinges on controlled inflammation, angiogenesis, and remodeling facilitated by the exchange of cytokines and growth factors. Comorbid conditions can disrupt this process, leading to significant morbidity and mortality. Stem cell therapy has emerged as a promising strategy for enhancing wound healing, utilizing cells from diverse sources such as endothelial progenitor cells, bone marrow, adipose tissue, dermal, and inducible pluripotent stem cells. In this systematic review, we comprehensively investigated stem cell therapies in chronic wounds, summarizing the clinical, translational, and primary literature. A systematic search across PubMed, Embase, Web of Science, Google Scholar, and Cochrane Library yielded 22,454 articles, reduced to 44 studies after rigorous screening. Notably, adipose tissue-derived mesenchymal stem cells (AD-MSCs) emerged as an optimal choice due to their abundant supply, easy isolation, ex vivo proliferative capacities, and pro-angiogenic factor secretion. AD-MSCs have shown efficacy in various conditions, including peripheral arterial disease, diabetic wounds, hypertensive ulcers, bullous diabeticorum, venous ulcers, and post-Mohs micrographic surgery wounds. Delivery methods varied, encompassing topical application, scaffold incorporation, combination with plasma-rich proteins, and atelocollagen administration. Integration with local wound care practices resulted in reduced pain, shorter healing times, and improved cosmesis. Stem cell transplantation represents a potential therapeutic avenue, as transplanted stem cells not only differentiate into diverse skin cell types but also release essential cytokines and growth factors, fostering increased angiogenesis. This approach holds promise for intractable wounds, particularly chronic lower-leg wounds, and as a post-Mohs micrographic surgery intervention for healing defects through secondary intention. The potential reduction in healthcare costs and enhancement of patient quality of life further underscore the attractiveness of stem cell applications in wound care. This systematic review explores the clinical utilization of stem cells and stem cell products, providing valuable insights into their role as ancillary methods in treating chronic wounds.

Guidelines on interventions to enhance healing of foot ulcers in people with diabetes (IWGDF 2023 update)

AIMS

Principles of wound management, including debridement, wound bed preparation, and newer technologies involving alternation of wound physiology to facilitate healing, are of utmost importance when attempting to heal a chronic diabetes-related foot ulcer. However, the rising incidence and costs of diabetes-related foot ulcer management necessitate that interventions to enhance wound healing of chronic diabetes-related foot ulcers are supported by high-quality evidence of efficacy and cost effectiveness when used in conjunction with established aspects of gold-standard multidisciplinary care. This is the 2023 International Working Group on the Diabetic Foot (IWGDF) evidence-based guideline on wound healing interventions to promote healing of foot ulcers in persons with diabetes. It serves as an update of the 2019 IWGDF guideline.

MATERIALS AND METHODS

We followed the GRADE approach by devising clinical questions and important outcomes in the Patient-Intervention-Control-Outcome (PICO) format, undertaking a systematic review, developing summary of judgements tables, and writing recommendations and rationale for each question. Each recommendation is based on the evidence found in the systematic review and, using the GRADE summary of judgement items, including desirable and undesirable effects, certainty of evidence, patient values, resources required, cost effectiveness, equity, feasibility, and acceptability, we formulated recommendations that were agreed by the authors and reviewed by independent experts and stakeholders.

RESULTS

From the results of the systematic review and evidence-to-decision making process, we were able to make 29 separate recommendations. We made a number of conditional supportive recommendations for the use of interventions to improve healing of foot ulcers in people with diabetes. These include the use of sucrose octasulfate dressings, the use of negative pressure wound therapies for post-operative wounds, the use of placental-derived products, the use of the autologous leucocyte/platelet/fibrin patch, the use of topical oxygen therapy, and the use of hyperbaric oxygen. Although in all cases it was stressed that these should be used where best standard of care was not able to heal the wound alone and where resources were available for the interventions.

CONCLUSIONS

These wound healing recommendations should support improved outcomes for people with diabetes and ulcers of the foot, and we hope that widescale implementation will follow. However, although the certainty of much of the evidence on which to base the recommendations is improving, it remains poor overall. We encourage not more, but better quality trials including those with a health economic analysis, into this area.

Extracellular vesicles modulate key signalling pathways in refractory wound healing

Chronic wounds are wounds that cannot heal properly due to various factors, such as underlying diseases, infection or reinjury, and improper healing of skin wounds and ulcers can cause a serious economic burden. Numerous studies have shown that extracellular vesicles (EVs) derived from stem/progenitor cells promote wound healing, reduce scar formation and have significant advantages over traditional treatment methods. EVs are membranous particles that carry various bioactive molecules from their cellular origins, such as cytokines, nucleic acids, enzymes, lipids and proteins. EVs can mediate cell-to-cell communication and modulate various physiological processes, such as cell differentiation, angiogenesis, immune response and tissue remodelling. In this review, we summarize the recent advances in EV-based wound healing, focusing on the signalling pathways that are regulated by EVs and their cargos. We discuss how EVs derived from different types of stem/progenitor cells can promote wound healing and reduce scar formation by modulating the Wnt/β-catenin, phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin, vascular endothelial growth factor, transforming growth factor β and JAK-STAT pathways. Moreover, we also highlight the challenges and opportunities for engineering or modifying EVs to enhance their efficacy and specificity for wound healing.

Triazolothiadiazine derivative positively modulates CXCR4 signaling and improves diabetic wound healing

Development of specific therapies that target and accelerate diabetic wound repair is an urgent need to alleviate pain and suffering and the huge socioeconomic burden of this debilitating disease. C-X-C Motif Chemokine Ligand 12 (CXCL12) also know an stromal cell-derived factor 1α (SDF-1α) is a chemokine that binds the CXC chemokine receptor type 4 (CXCR4) and activates downstream signaling resulting in recruitment of hematopoietic cells to locations of tissue injury and promotes tissue repair. In diabetes, low expression of CXCL12 correlates with impaired wound healing. Activation of CXCR4 receptor signaling with agonists or positive allosteric modulators (PAMs) provides a potential for small molecule therapeutic discovery and development. We recently reported high throughput screening and identification of the CXCR4 partial agonist UCUF-728, characterization of in vitro activity and reduced wound closure time in diabetic mice at 100 μM as a proof-of-concept study. We report here, the discovery of a second chemical scaffold demonstrating increased agonist potency and represented by thiadiazine derivative, UCUF-965. UCUF-965 is a potent partial agonist of β-arrestin recruitment in CXCR4 receptor overexpressing cell line. Furthermore, UCUF-965 potentiates the CXCL12 maximal response in cAMP signaling pathway, activates CXCL12 stimulated migration in lymphoblast cells and modulates the levels of specific microRNA involved in the complex wound repair process, specifically in mouse fibroblasts. Our results indicate that UCUF-965 acts as a PAM agonist of the CXCR4 receptor. Furthermore, UCUF-965 enhanced angiogenesis markers and reduced wound healing time by 36% at 10.0 μM in diabetic mice models compared to untreated control.

Putative circulating adipose tissue-derived stem cells, obesity, and metabolic syndrome features

PURPOSE

In mice, adipose tissue-derived stem cells (ASCs) reach the systemic circulation and establish ectopic adipose depots fostering insulin resistance, but whether this occurs in humans is unknown. We examined circulating ASCs in individuals with various combination of metabolic syndrome traits.

METHODS

We enrolled patients attending a routine metabolic evaluation or scheduled for bariatric surgery. We quantified ASCs as CD34+CD45-CD31-(CD36+) cells in the stromal vascular fraction of subcutaneous and visceral adipose tissue samples and examined the presence and frequency of putative ASCs in peripheral blood.

RESULTS

We included 111 patients (mean age 59 years, 55% males), 40 of whom were scheduled for bariatric surgery. The population of CD34+CD45-CD31- ASCs was significantly more frequent in visceral than subcutaneous adipose depots (10.4 vs 4.1% of the stromal vascular fraction; p < 0.001), but not correlated with BMI or metabolic syndrome traits. The same phenotype of ASCs was detectable in peripheral blood of 58.6% of patients. Those with detectable circulating ASCs had significantly higher BMI (37.8 vs 33.3 kg/m2; p = 0.003) and waist (111.2 vs 105.4 cm; p = 0.001), but no difference in other metabolic syndrome traits (p = 0.84). After bariatric surgery, patients with detectable circulating ASCs had greater BMI reductions at 6 months (- 10.4 vs - 7.8 kg/m2; p = 0.014).

CONCLUSION

Presence of putative circulating ASCs, antigenically similar to those observed in the adipose tissue, is associated with greater adiposity and larger BMI reduction after surgery, but not with clinical signs of metabolic impairment. The role of circulating ASCs in adipose tissue biology and systemic metabolism deserves further investigation.

A phase I, first-in-human study to evaluate the safety and tolerability, pharmacokinetics, and pharmacodynamics of MRG-001 in healthy subjects

Preclinical studies demonstrate that pharmacological mobilization and recruitment of endogenous bone marrow stem cells and immunoregulatory cells by a fixed-dose drug combination (MRG-001) improves wound healing, promotes tissue regeneration, and prevents allograft rejection. In this phase I, first-in-human study, three cohorts receive subcutaneous MRG-001 or placebo, every other day for 5 days. The primary outcome is safety and tolerability of MRG-001. Fourteen subjects received MRG-001 and seven received a placebo. MRG-001 is safe over the selected dose range. There are no clinically significant laboratory changes. The intermediate dose group demonstrates the most significant white blood cell, stem cell, and immunoregulatory cell mobilization. PBMC RNA sequencing and gene set enrichment analysis reveal 31 down-regulated pathways in the intermediate MRG-001 dose group compared with no changes in the placebo group. MRG-001 is safe across all dose ranges. MRG-001 may be a clinically useful therapy for immunoregulation and tissue regeneration (ClinicalTrials.gov: NCT04646603).

Stem cells in plastic surgery and aesthetic medicine

Stem cells (SCs) have multiple applications in today's medicine including aesthetic dermatology and plastic surgery. The purpose of this paper is to review some clinical use of mesenchymal SCs. The main focus was put on adipose tissue-derived stem cells (ADSCs) as these cells are easy to harvest and because of their properties showed great potential in many studies, where they proved to accelerate wound healing, reduce scars, cause hair regrowth, or rejuvenate skin. Furthermore, when added to lipofilling procedures, such as breast augmentation they enhance fat graft survival and provide satisfying results. Currently, many different strategies for using SCs in treatments are developed with great efficacy, however, there are still many limitations and concerns regarding their clinical use.

[Bioinformatics Analysis of Hub Genes of Diabetic Foot Ulcer and Their Biofunctions]

OBJECTIVE

To explore the hub genes associated with the pathogenesis and healing of diabetic foot ulcer (DFU) and their biological functions through bioinformatics analysis of transcriptome sequencing data.

METHODS

The transcriptome sequencing datasets of DFU were selected from Gene Expression Omnibus (GEO) database, and the data were regrouped and normalized for bioinformatics analysis. The skin transcriptome sequencing datasets of DFU patients were compared with those of normal controls and the transcriptome sequencing datasets of skin from ulcerous wound edge of DFU patients were compared with those of non-ulcerous skin of DFU patients so that differentially expressed genes were identified, pathway enrichment and protein-to-protein interaction (PPI) analyses were performed, hub genes were found through nodal analysis, and receiver operating characteristic (ROC) curve was applied to a testing dataset to validate the diagnostic efficiency of the hub genes related to DFU. The intersecting genes from the two sets of analyses were again subjected to pathway enrichment and PPI analyses to screen for hub genes associated with DFU wound healing. What's more, gene set enrichment analysis (GSEA) was carried out on relevant samples to probe for the possible functions and pathway of non-significant genes in DFU.

RESULTS

A total of 620 up-regulated differentially expressed genes and 196 down-regulated differentially expressed genes were identified in the training dataset which compared DFU patients with non-diabetic patients. The functions of these genes were enriched in the metabolism of terpenoids and polyketides, signaling molecules and interaction, phospholipase D signaling pathway, propanoate metabolism, PI3K-Akt signaling pathway, Toll-like receptor signaling pathway, pyrimidine metabolism, IL-17 signaling pathway, Rap1 signaling pathway, etc. A total of 10 hub genes were identified with the PPI network. Among them, BGN's value of the area under the curve of ROC analysis was 0.714 and CCND1's was 0.712. In the sequencing analysis of ulcerous wound edge of DFU patients and non-ulcerous skin of DFU patients, 4072 up-regulated genes and 911 down-regulated genes were identified, of which, 372 genes were also detected in the differentially expressed genes of DFU. The functions of these differentially expressed genes were enriched in phospholipase D signaling pathway, xenobiotics biodegradation and energy metabolism, glutathione metabolism, pyrimidine metabolism, ErbB signaling pathway, melanin production, etc. A total of 7 hub genes were identified from PPI network. In GSEA analysis, pathways including pentose and glucuronate interconversions and homologous recombination, nicotinate and nicotinamide metabolism, neuroactive ligand receptor interaction, maturity-onset diabetes of the young, butanoate metabolism, lysine degradation, pantothenate and coenzyme A biosynthesis, riboflavin metabolism, steroid hormone biosynthesis, and valine, leucine and isoleucine degradation showed significant expression differences between DFU patients and normal controls.

CONCLUSION

Bioinformatics analysis results suggest that BGN and CCND1 are potential biomarkers for predicting DFU; CXCL12, TLR4, JAK2, PPARA, UBC, DCN, KDR, and ARNTL are the hub genes of DFU, while CXCL8, CXCL12, TXN, SLIT3, KRT14, KIT, and NEO1 are the hub genes related to wound healing of DFU.

Impaired haematopoietic stem / progenitor cell traffic and multi-organ damage in diabetes

During antenatal development, hematopoietic stem/progenitor cells (HSPCs) arise from a specialized endothelium and migrate from the extraembryonic mesoderm to the fetal liver before establishing hematopoiesis in the bone marrow (BM). It is still debated whether, in adulthood, HSPCs display such ontologic overlap with vascular cells and capacity for endothelial differentiation. Yet, adult HSPCs retain a prominent migratory activity and traffic in the bloodstream to secondary lymphoid organs and all peripheral tissues, before eventually returning to the BM. While patrolling parenchymatous organs, HSPCs locate close to the vasculature, where they establish local hematopoietic islands and contribute to tissue homeostasis by paracrine signals. Solid evidence shows that diabetes mellitus jeopardizes the traffic of HSPCs from BM to the circulation and peripheral tissues, a condition called “mobilopathy.” A reduction in the levels of circulating HSPCs is the most immediate and apparent consequence, which has been consistently observed in human diabetes, and is strongly associated with future risk for multi-organ damage, including micro- and macro-angiopathy. But the shortage of HSPCs in the blood is only the visible tip of the iceberg. Abnormal HSPC traffic results from a complex interplay among metabolism, innate immunity, and hematopoiesis. Notably, mobilopathy is mechanistically connected with diabetes-induced myelopoiesis. Impaired traffic of HSPCs and enhanced generation of pro-inflammatory cells synergize for tissue damage and impair the resolution of inflammation. We herein summarize the current evidence that diabetes affects HSPC traffic, which are the causes and consequences of such alteration, and how it contributes to the overall disease burden.

Hematopoietic and Nonhematopoietic p66Shc Differentially Regulates Stem Cell Traffic and Vascular Response to Ischemia in Diabetes

Aims: Peripheral artery disease (PAD) is a severe complication of diabetes, characterized by defective traffic of hematopoietic stem/progenitor cells (HSPCs). We examined the hematopoietic versus nonhematopoietic role of p66Shc in regulating HSPC traffic and blood flow recovery after ischemia in diabetic mice. Results: Using streptozotocin-induced diabetes, chimeric mice with green fluorescent protein (GFP)⁺ bone marrow (BM), and the hind limb ischemia model, we found that the physiologic mobilization and homing of HSPCs were abolished by diabetes, along with impaired vascular recovery. Hematopoietic deletion of p66Shc, obtained by transplanting p66Shc^-/- BM cells into wild-type (Wt) recipients, but not nonhematopoietic deletion, constrained hyperglycemia-induced myelopoiesis, rescued postischemic HSPC mobilization, and improved blood flow recovery in diabetic mice. In Wt diabetic mice transplanted with BM cells from GFP⁺p66Shc^-/- mice, the amount of HSPCs homed to ischemic muscles was greater than in mice transplanted with GFP⁺p66Shc^+/+ cells, with recruited cells displaying higher expression of adhesion molecules and Vegf. In 40 patients with diabetes, p66Shc gene expression in mononuclear cells was correlated with myelopoiesis and elevated in the presence of PAD. In 13 patients with diabetes and PAD, p66Shc expression in HSPC-mobilized peripheral blood cells was inversely correlated with VEGF expression. Innovation: For the first time, we dissect the role of hematopoietic versus nonhematopoietic p66Shc in regulating HSPC traffic and ischemic responses. Conclusion: Hematopoietic deletion of p66Shc was sufficient to rescue HSPC mobilization and homing in diabetes after ischemia and improved blood flow recovery. Inhibiting p66Shc in blood cells may be a novel strategy to counter PAD in diabetes. Antioxid. Redox Signal. 36, 593-607. Clinical Trial No.: NCT02790957.

Cell Therapy for Critical Limb Ischemia: Advantages, Limitations, and New Perspectives for Treatment of Patients with Critical Diabetic Vasculopathy

PURPOSE OF REVIEW

To provide a highlight of the current state of cell therapy for the treatment of critical limb ischemia in patients with diabetes.

RECENT FINDINGS

The global incidence of diabetes is constantly growing with consequent challenges for healthcare systems worldwide. In the UK only, NHS costs attributed to diabetic complications, such as peripheral vascular disease, amputation, blindness, renal failure, and stroke, average £10 billion each year, with cost pressure being estimated to get worse. Although giant leaps forward have been registered in the scope of early diagnosis and optimal glycaemic control, an effective treatment for critical limb ischemia is still lacking. The present review aims to provide an update of the ongoing work in the field of regenerative medicine. Recent advancements but also limitations imposed by diabetes on the potential of the approach are addressed. In particular, the review focuses on the perturbation of non-coding RNA networks in progenitor cells and the possibility of using emerging knowledge on molecular mechanisms to design refined protocols for personalized therapy. The field of cell therapy showed rapid progress but has limitations. Significant advances are foreseen in the upcoming years thanks to a better understanding of molecular bottlenecks associated with the metabolic disorders.

Diabetes pharmacotherapy and circulating stem/progenitor cells. State of the art and evidence gaps

Diabetes is burdened with the development of several end-organ complications leading to excess mortality. Though the causes of such organ damage are far from being clarified, diabetes has been redefined as a disease of impaired damage control, wherein ongoing damage is not adequately compensated by activation of repair processes. Bone marrow-derived hematopoietic stem/progenitor cells (HSPCs) and their descendants endothelial progenitor cells (EPCs) have been extensively studied as major players in tissue homeostasis as well as biomarkers of diabetic complication risk. Thus, strategies to raise the levels of circulating HSPCs/EPCs have attracted interest for their potential to modify the future risk of complications. We herein discuss state-of-the-art of the effects exerted by diabetes pharmacotherapy on such cell populations. Further, we highlight which outstanding questions remain to be addressed for a more comprehensive understanding of this topic.

Stem cell mobilization with plerixafor and healing of diabetic ischemic wounds: A phase IIa, randomized, double-blind, placebo-controlled trial

Bone marrow‐derived cells contribute to tissue repair, but traffic of hematopoietic stem/progenitor cells (HSPCs) is impaired in diabetes. We therefore tested whether HSPC mobilization with the CXCR4 antagonist plerixafor improved healing of ischemic diabetic wounds. This was a pilot, phase IIa, double‐blind, randomized, placebo‐controlled trial (NCT02790957). Patients with diabetes with ischemic wounds were randomized to receive a single subcutaneous injection of plerixafor or saline on top of standard medical and surgical therapy. The primary endpoint was complete healing at 6 months. Secondary endpoints were wound size, transcutaneous oxygen tension (TcO₂), ankle‐brachial index (ABI), amputations, and HSPC mobilization. Twenty‐six patients were enrolled: 13 received plerixafor and 13 received placebo. Patients were 84.6% males, with a mean age of 69 years. HSPC mobilization was successful in all patients who received plerixafor. The trial was terminated after a preplanned interim analysis of 50% of the target population showed a significantly lower healing rate in the plerixafor vs the placebo group. In the final analysis data set, the rate of complete healing was 38.5% in the plerixafor group vs 69.2% in the placebo group (chi‐square P = .115). Wound size tended to be larger in the plerixafor group for the entire duration of observation. No significant difference was noted for the change in TcO₂ and ABI or in amputation rates. No other safety concern emerged. In conclusion, successful HSPC mobilization with plerixafor did not improve healing of ischemic diabetic wounds. Contrary to what was expected, outside the context of hematological disorders, mobilization of diabetic HSPCs might exert adverse effects on wound healing.