The role of allogeneic platelet-rich plasma in patients with diabetic foot ulcer: Current perspectives and future challenges

Platelet-rich plasma-derived exosomes accelerate the healing of diabetic foot ulcers by promoting macrophage polarization toward the M2 phenotype

Diabetic foot ulcers (DFUs) impose a significant clinical and socioeconomic burden on patients and healthcare systems. Although platelet-rich plasma (PRP) and platelet-rich plasma-derived exosomes (PRP-Exos) have emerged as promising therapeutic agents in tissue regeneration, the mechanisms underlying the immunomodulatory effects of PRP and PRP-Exos-particularly their role in macrophage polarization-remain poorly understood. In this study, we isolated and characterized PRP-Exos and systematically evaluated their therapeutic potential in diabetic wound healing via comprehensive in vivo and in vitro experiments. Our results revealed that both PRP-gel and PRP-Exos significantly enhanced diabetic wound healing by promoting macrophage polarization toward the anti-inflammatory M2 phenotype. These findings suggest that PRP-Exos represent a novel and effective therapeutic strategy for DFUs, providing a robust rationale for future clinical translation.

Platelet concentrates in diabetic foot ulcers: A comparative review of PRP, PRF, and CGF with case insights

Diabetic foot ulcers (DFUs) are severe complications of diabetes, often leading to chronic wounds, amputations, and increased mortality risk. Platelet concentrates (PCs)-natural biomaterials utilized in regenerative medicine-have garnered attention for their capacity to enhance tissue repair and wound healing. This study reviews the preparation methods, biological mechanisms, and clinical efficacy of three generations of PCs: platelet-rich plasma (PRP), platelet-rich fibrin (PRF), and concentrated growth factors (CGF). Comparative analysis reveals that PRP, the first generation, provides abundant growth factors but relies on anticoagulants, which may hinder fibrin formation and tissue adhesion. PRF, as the second generation, eliminates anticoagulants, forming a fibrin matrix that sustains growth factor release and enhances cell migration. CGF, the latest advancement, employs refined centrifugation to achieve higher growth factor concentrations and a denser fibrin matrix, accelerating tissue regeneration. Case series results demonstrated superior wound healing outcomes with CGF, including faster epithelialization and reduced healing time compared to PRP and PRF. These findings underscore CGF's potential as the most effective PC for managing DFUs, supporting its broader clinical adoption in advanced wound care.

Emerging treatment strategies in dry eye disease: Potential of blood-derived approaches and natural plant-based products

Dry eye disease (DED) is a common ocular condition characterized by chronic inflammation and tear film disruption. It affects millions of people worldwide, causing significant eye discomfort and vision disturbances. Despite its prevalence, DED remains a complex condition that is not yet fully understood. It can arise from various ocular pathologies, including endocrinological disorders such as diabetes and Graves' orbitopathy. Natural products, including plant- and blood-based therapies, have shown promise in alleviating DED symptoms and may represent effective therapeutic approaches. In this study, we review recent research on natural product treatments for DED, focusing on blood-derived therapies (e.g., autologous serum, albumin serum, and allogeneic serum) and plant-based compounds such as omega-3 fatty acids (O3FA), omega-6 fatty acids (O6FA), antioxidants, polyphenols, and flavonoids. Additionally, we examine the efficacy, mechanisms of action, and delivery systems of these treatments, highlighting the potential of blood-derived therapies, polyphenols, and flavonoids to improve or treat DED through multiple mechanisms. However, the use of these natural products as instilled drugs is limited by challenges such as solubility, stability, and biological barriers. Finally, we discuss drug delivery systems and structural modifications designed to enhance the therapeutic effects of these treatments, emphasizing their potential in managing DED.

Platelet extracellular vesicles-loaded hydrogel bandages for personalized wound care

Autologous or allogeneic platelet-derived extracellular vesicles (pEVs) show potential in enhancing tissue recovery and healing chronic wounds. pEVs promote neovascularization and cell migration while reducing inflammation, oxidative stress, and scarring. However, their efficacy in clinical settings is challenged by their susceptibility to washout by wound exudate. Hydrogel-based bandages are effective carriers that stabilize pEVs for optimal personalized wound care. These bandages can be tailored for easy removal to minimize damage to regenerated tissue and can incorporate antibacterial or moisture-retaining properties. Furthermore, the possibility of integrating sensors in the wound bed will enable a theragnostic approach to healing. This review explores advancements in pEV-loaded hydrogels and their potential for personalized clinical applications.

Current trends in the design and fabrication of PRP-based scaffolds for tissue engineering and regenerative medicine

Blood-derived biomaterials with high platelet content have recently emerged as attractive products for tissue engineering and regenerative medicine (TERM). Platelet-derived bioactive molecules have been shown to play a role in wound healing and tissue regeneration processes by promoting collagen synthesis, angiogenesis, cell proliferation, migration, and differentiation. Given their regenerative potential, platelet-rich blood derivatives have become a promising treatment option for use in a variety of conditions. Platelet-Rich Plasma (PRP), one of the platelet-rich blood derivatives, is a platelet concentrate suspended in a small volume of blood plasma obtained from whole blood. Due to its potential clinical benefits, PRP is widely used alone or in combination with various biomaterials/scaffolds in different fields of medicine and has shown promising results in wound healing. The recent growing interest in the development of PRP-based scaffolds also reveals new perspectives on the use of PRP or platelet lysate in TERM. This topical review contains a comprehensive summary of recent trends in the fabrication of PRP-based scaffolds that can deliver growth factors, serve as mechanical support for cells, and have therapeutic or regenerative properties. The article briefly focuses on diverse PRP-based constructs using PRP as a scaffolding material, their current fabrication approaches as well as the challenges encountered and provides a selection of existing strategies and new insights.

Human platelet lysate: a potential therapeutic for intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a major public health challenge worldwide, and is associated with elevated rates of mortality, disability, and morbidity, especially in low- and middle-income nations. However, our knowledge of the detailed molecular processes involved in ICH remains insufficient, particularly those involved in the secondary injury stage, resulting in a lack of effective treatments for ICH. Human platelet lysates (HPL) are abundant in bioactive factors, and numerous studies have demonstrated their beneficial effects on neurological diseases, including their anti-neuroinflammatory ability, anti-oxidant effects, maintenance of blood-brain barrier integrity, and promotion of neurogenesis. In this review, we thoroughly explore the potential of HPL for treating ICH from three critical perspectives: the rationale for selecting HPL as a treatment for ICH, the mechanisms through which HPL contributes to ICH management, and the additional measures necessary for HPL as a treatment for ICH. We elucidate the role of platelets in ICH pathophysiology and highlight the limitations of the current treatment options and advancements in preclinical research on the application of HPL in neurological disorders. Furthermore, historical developments and preparation methods of HPL in the field of biomedicine are discussed. Additionally, we summarize the bioactive molecules present in HPL and their potential therapeutic effects in ICH. Finally, we outline the issues that must be addressed regarding utilizing HPL as a treatment modality for ICH.

Effect of aspirin on platelet-rich plasma of diabetes mellitus with lower extremity atherosclerosis

Aim: Platelet-rich plasma (PRP), enriched with multiple growth factors, is a promising adjunctive therapy for diabetic foot ulcers (DFUs). As a classic anti-platelet drug for diabetic patients, the effects of aspirin on the content of growth factors in PRP remains unclear.Methods: Our study enrolled diabetic patients who were currently taking or not taking aspirin as the research subjects, with healthy volunteers as the control. PRP from these individuals was activated with glucose calcium and thrombin. Growth factors levels in PRP activated supernatant (PRP-AS) and wound healing ability of platelet gel (PG) in the full-thickness skin defect diabetic mouse model were compared.Results: We found the level of growth factors in PRP-AS derived from two groups of diabetic patients were not statistically different, whereas both lower than that from healthy volunteers. Similarly, we found better wound healing ability of PG from healthy volunteers than those from diabetic patients, but no difference between the two groups of diabetic patients in the mouse model.Discussion: Aspirin does not interfere with autologous PRP therapy when using calcium gluconate and thrombin as agonists. However considering the content of growth factors, PRP from healthy volunteers is a preferable option for promoting DFU repair.

Platelet-Rich Plasma in Diabetic Foot Ulcer Healing: Contemplating the Facts

Diabetic foot ulcers (DFUs), debilitating complication of diabetes, often lead to amputation even in the presence of current advanced treatment for DFUs. Platelet-rich plasma (PRP) containing growth factors and other proteins has been suggested as a potent therapeutic in promoting DFU healing. PRP is safe and effective in improving the DFU healing rate, decreasing healing time, and making chronic wounds viable for treatment. Though PRP is safe and effective in promoting DFU healing, there are inconsistencies in clinical outcomes. These varying results may be due to various concentrations of PRP being used. Most studies report dosage and timing, but none have reported the concentration of various factors. This is important, as the concentration of factors in PRP can vary significantly with each preparation and may directly impact the healing outcome. This critical review discusses the limiting factors and issues related to PRP therapy and future directives. A systematic search of PubMed and Google Scholar was performed with keywords including diabetic foot ulcer, ulcer healing, platelet-rich plasma, DFU treatment, and PRP limitations and efficacy, alone or in combination, to search the related articles. The articles describing DFU and the use of PRP in DFU healing were included. The existing literature suggests that PRP is effective and safe for promoting DFU healing, but larger clinical trials are needed to improve clinical outcomes. There is a need to consider multiple factors including the role of epigenetics, lifestyle modification, and the percentage composition of each constituent in PRP.

Hypoxia Preconditioned Serum Hydrogel (HPS-H) Accelerates Dermal Regeneration in a Porcine Wound Model

Harnessing the body's intrinsic resources for wound healing is becoming a rapidly advancing field in regenerative medicine research. This study investigates the effects of the topical application of a novel porcine Hypoxia Preconditioned Serum Hydrogel (HPS-H) on wound healing using a minipig model over a 21-day period. Porcine HPS exhibited up to 2.8× elevated levels of key angiogenic growth factors (VEGF-A, PDGF-BB, and bFGF) and demonstrated a superior angiogenic effect in a tube formation assay with human umbilical endothelial cells (HUVECs) in comparison to porcine normal serum (NS). Incorporating HPS into a hydrogel carrier matrix (HPS-H) facilitated the sustained release of growth factors for up to 5 days. In the in vivo experiment, wounds treated with HPS-H were compared to those treated with normal serum hydrogel (NS-H), hydrogel only (H), and no treatment (NT). At day 10 post-wounding, the HPS-H group was observed to promote up to 1.7× faster wound closure as a result of accelerated epithelialization and wound contraction. Hyperspectral imaging revealed up to 12.9% higher superficial tissue oxygenation and deep perfusion in HPS-H-treated wounds at day 10. The immunohistochemical staining of wound biopsies detected increased formation of blood vessels (CD31), lymphatic vessels (LYVE-1), and myofibroblasts (alpha-SMA) in the HPS-H group. These findings suggest that the topical application of HPS-H can significantly accelerate dermal wound healing in an autologous porcine model.

Efficacy and safety of allogeneic platelet-rich plasma in chronic wound treatment: a meta-analysis of randomized controlled trials

Allogeneic platelet-rich plasma (al-PRP) is gaining attention in clinical practice for treating chronic refractory wounds, though research results remain controversial. To assess the clinical efficacy of al-PRP for chronic refractory wounds. Databases including PubMed, Cochrane Library, Embase, CNKI, SinoMed, VIP, and WFPD were searched for randomized controlled trials comparing al-PRP with conventional treatments up to October 2023. Two researchers independently screened studies, extracted data, and assessed quality. Statistical analysis was conducted using RevMan 5.4, and potential publication bias was assessed and corrected using funnel plots and Egger's test. Twelve studies with 717 cases were included. Meta-analysis showed al-PRP significantly improved outcomes compared to non-al-PRP treatments: increased healing rate (RR 2.72, 95% CI 1.77-4.19, p < 0.00001), shortened healing time (SMD - 1.03, 95% CI -1.31 to -0.75, p < 0.00001), improved efficacy rate (RR 1.19, 95% CI 1.10-1.28, p < 0.00001), increased wound shrinkage (MD 35.65%, 95% CI 21.65-49.64, p < 0.00001), and reduced hospital stays (MD -2.62, 95% CI -4.35 to -0.90, p = 0.003). Al-PRP is a feasible, effective, and safe biological therapy for chronic refractory wounds.Trial registration: PROSPERO Identifier CRD42022374920.

Platelet-rich plasma promotes wound repair in diabetic foot ulcer mice via the VEGFA/VEGFR2/ERK pathway

Diabetic foot ulcers (DFUs) are a severe microvascular complication. Platelet-rich plasma (PRP) pitches in DFU treatment. This study explored the mechanism of PRP facilitating wound repair in DFU mice via vascular endothelial growth factor A (VEGFA)/VEGF receptor 2 (VEGFR2)/extracellular signal-regulated kinase (ERK) pathway. The DFU mouse model was established, with wound skin injected with PRP, followed by the detections of wound area, histopathological changes, and CD31-positive cells. IL-6/TNF-α/VEGFA/VEGFR2/p-VEGFR2/(ERK1/2)/(p-ERK1/2) levels in wound tissue homogenates were assessed. VEGFA-VEGFR2 interaction was evaluated. PRP-treated DFU mice were simultaneously treated with fruquintinib/PD98059. PRP reduced wound area, IL-6 and TNF-α levels, elevated epidermal dermal thickness, CD31-positive cell number, and aligned tissue structure, which were mitigated by fruquintinib/PD98059. PRP promoted VEGFR2 phosphorylation. PRP and fruquintinib/PD98059 abated p-VEGFR2/VEGFR2 or p-ERK1/2/ERK1/2 levels in DFU mice. PRP activated the ERK pathway through VEGFA/VEGFR2. Collectively, PRP promoted VEGFR2 phosphorylation and activated the ERK pathway, thereby facilitating wound repair in DFU mice.

Platelet-Rich Plasma (PRP) Based on Simple and Efficient Integrated Preparation Precises Quantitatively for Skin Wound Repair

Platelet-rich plasma (PRP) has become an important regenerative therapy. However, the preparation method of PRP has not been standardized, and the optimal platelet concentration for PRP used in skin wound repair is unclear, leading to inconsistent clinical efficacy of PRP. Therefore, the development of standardized preparation methods for PRP and the investigation of the dose-response relationship between PRP with different platelet concentrations and tissue regeneration plays an important role in the development and clinical application of PRP technology. This study has developed an integrated blood collection device from blood drawing to centrifugation. Response surface methodology was employed to optimize the preparation conditions, ultimately achieving a platelet recovery rate as high as 95.74% for PRP (with optimal parameters: centrifugation force 1730× g, centrifugation time 10 min, and serum separation gel dosage 1.4 g). Both in vitro and in vivo experimental results indicate that PRP with a (2×) enrichment ratio is the most effective in promoting fibroblast proliferation and skin wound healing, with a cell proliferation rate of over 150% and a wound healing rate of 78% on day 7.

Exosomal miRNA-26b-5p from PRP suppresses NETs by targeting MMP-8 to promote diabetic wound healing

The utilization of platelet-rich plasma (PRP) has exhibited potential as a therapeutic approach for the management of diabetic foot ulcers (DFUs). However, it is currently not well understood how the diabetic environment may influence PRP-derived exosomes (PRP-Exos) and their potential impact on neutrophil extracellular traps (NETs). This study aims to investigate the effects of the diabetic environment on PRP-Exos, their communication with neutrophils, and the subsequent influence on NETs and wound healing. Through bulk-seq and Western blotting, we confirmed the increased expression of MMP-8 in DFUs. Additionally, we discovered that miRNA-26b-5p plays a significant role in the communication between DFUs and PRP-Exos. In our experiments, we found that PRP-Exos miR-26b-5p effectively improved diabetic wound healing by inhibiting NETs. Further tests validated the inhibitory effect of miR-26b-5p on NETs by targeting MMP-8. Both in vitro and in vivo experiments showed that miRNA-26b-5p from PRP-Exos promoted wound healing by reducing neutrophil infiltration through its targeting of MMP-8. This study establishes the importance of miR-26b-5p in the communication between DFUs and PRP-Exos, disrupting NETs formation in diabetic wounds by targeting MMP-8. These findings provide valuable insights for developing novel therapeutic strategies to enhance wound healing in individuals suffering from DFUs.

Efficacy of Platelet-Rich Plasma in the Treatment of Diabetic Foot Ulcer

Introduction Diabetic foot complications leading to limb amputations pose a global health concern. Platelet-rich plasma (PRP) gel has emerged as a promising method for ulcer healing, leveraging the growth factors provided by autologous PRP to enhance tissue healing. Therefore, we aimed to assess the frequency of the success of PRP therapy in the treatment of non-healing diabetic foot ulcers. Methods This quasi-experimental study, conducted in Lahore, Pakistan, from April 2021 to October 2022, enrolled 80 eligible individuals with non-responsive diabetic foot ulcers using a consecutive sampling technique. Inclusion criteria involved patients of both genders, aged 45-75 years, with unhealed diabetic foot ulcers, and exclusion criteria considered factors such as recurrent ulcers at the same site, smoking, and immunosuppressive or anticoagulant drug therapy. Baseline demographic details, ulcer measurements using a scale, and AutoCAD (Autodesk, Inc., San Francisco, California, United States)-assisted quantification of ulcer base were recorded. Autologous PRP injections were administered following strict aseptic protocols, with dressing changes and assessments performed at specified intervals over four weeks. Treatment success, defined as >90% healing after four weeks, was the primary outcome. Data analysis utilized IBM SPSS Statistics for Windows, Version 26.0 (Released 2019; IBM Corp., Armonk, New York, United States), employing post-stratification chi-square and t-tests where appropriate for significant differences. Results The mean age of the patients was 60.40 ± 9.72 years, the mean duration of diabetes was 9.48 ± 2.21 years, and the mean ulcer duration was 11.41 ± 1.63 months. The treatment success rate was 63.7%. Age, gender, and disease duration showed no significant impact on treatment success. However, patients with a normal BMI and shorter ulcer duration exhibited a significantly higher success rate (p <0.001 and p = 0.002, respectively). Conclusions This study reaffirms the efficacy of PRP in treating non-healing diabetic foot ulcers, aligning with previous research. Despite a slightly lower success rate compared to literature reports, PRP remains a promising agent for managing diabetic foot ulcers.

Pretreatment with platelet-rich plasma protects against ischemia-reperfusion induced flap injury by deactivating the JAK/STAT pathway in mice

BACKGROUND

Ischemia-reperfusion (I/R) injury is a major cause of surgical skin flap compromise and organ dysfunction. Platelet-rich plasma (PRP) is an autologous product rich in growth factors, with tissue regenerative potential. PRP has shown promise in multiple I/R-induced tissue injuries, but its effects on skin flap injury remain unexplored.

METHODS

We evaluated the effects of PRP on I/R-injured skin flaps, optimal timing of PRP administration, and the involved mechanisms.

RESULTS

PRP protected against I/R-induced skin flap injury by improving flap survival, promoting blood perfusion and angiogenesis, suppressing oxidative stress and inflammatory response, and reducing apoptosis, at least partly via deactivating Janus kinase (JAK)-signal transducers and activators of transcription (STAT) signalling pathway. PRP given before ischemia displayed overall advantages over that given before reperfusion or during reperfusion. In addition, PRP pretreatment had a stronger ability to reverse I/R-induced JAK/STAT activation and apoptosis than AG490, a specific inhibitor of JAK/STAT signalling.

CONCLUSIONS

This study firstly demonstrates the protective role of PRP against I/R-injured skin flaps through negative regulation of JAK/STAT activation, with PRP pretreatment showing optimal therapeutic effects.

[Research advances on stem cell-based treatments in animal studies and clinical trials of lymphedema]

Objective

To summarize the progress of the roles and mechanisms of various types of stem cell-based treatments and their combination therapies in both animal studies and clinical trials of lymphedema.

Methods

The literature on stem cell-based treatments for lymphedema in recent years at home and abroad was extensively reviewed, and the animal studies and clinical trials on different types of stem cells for lymphedema were summarized.

Results

Various types of stem cells have shown certain effects in animal studies and clinical trials on the treatment of lymphedema, mainly through local differentiation into lymphoid endothelial cells and paracrine cytokines with different functions. Current research focuses on two cell types, adipose derived stem cells and bone marrow mesenchymal stem cells, both of which have their own advantages and disadvantages, mainly reflected in the therapeutic effect of stem cells, the difficulty of obtaining stem cells and the content in vivo. In addition, stem cells can also play a synergistic role in combination with other treatments, such as conservative treatment, surgical intervention, cytokines, biological scaffolds, and so on. However, it is still limited to the basic research stage, and only a small number of studies have completed clinical trials.

Conclusion

Stem cells have great transformation potential in the treatment of lymphedema, but there is no unified standard in the selection of cell types, the amount of transplanted cells, and the timing of transplantation.

Expanding applications of allogeneic platelets, platelet lysates, and platelet extracellular vesicles in cell therapy, regenerative medicine, and targeted drug delivery

Platelets are small anucleated blood cells primarily known for their vital hemostatic role. Allogeneic platelet concentrates (PCs) collected from healthy donors are an essential cellular product transfused by hospitals to control or prevent bleeding in patients affected by thrombocytopenia or platelet dysfunctions. Platelets fulfill additional essential functions in innate and adaptive immunity and inflammation, as well as in wound-healing and tissue-repair mechanisms. Platelets contain mitochondria, lysosomes, dense granules, and alpha-granules, which collectively are a remarkable reservoir of multiple trophic factors, enzymes, and signaling molecules. In addition, platelets are prone to release in the blood circulation a unique set of extracellular vesicles (p-EVs), which carry a rich biomolecular cargo influential in cell-cell communications. The exceptional functional roles played by platelets and p-EVs explain the recent interest in exploring the use of allogeneic PCs as source material to develop new biotherapies that could address needs in cell therapy, regenerative medicine, and targeted drug delivery. Pooled human platelet lysates (HPLs) can be produced from allogeneic PCs that have reached their expiration date and are no longer suitable for transfusion but remain valuable source materials for other applications. These HPLs can substitute for fetal bovine serum as a clinical grade xeno-free supplement of growth media used in the in vitro expansion of human cells for transplantation purposes. The use of expired allogeneic platelet concentrates has opened the way for small-pool or large-pool allogeneic HPLs and HPL-derived p-EVs as biotherapy for ocular surface disorders, wound care and, potentially, neurodegenerative diseases, osteoarthritis, and others. Additionally, allogeneic platelets are now seen as a readily available source of cells and EVs that can be exploited for targeted drug delivery vehicles. This article aims to offer an in-depth update on emerging translational applications of allogeneic platelet biotherapies while also highlighting their advantages and limitations as a clinical modality in regenerative medicine and cell therapies.

Hyaluronic acid-based dual network hydrogel with sustained release of platelet-rich plasma as a diabetic wound dressing

In recent years, the incidence of diabetic skin ulcers has increased. Because of its extremely high disability and fatality rate, it brings a huge burden to patients and society. Platelet-rich plasma (PRP) contains a large number of biologically active substances and is of great clinical value in the treatment of various wounds. However, its weak mechanical properties and the consequent abrupt release of active substances greatly limit its clinical application and therapeutic efficacy. Here, we chose hyaluronic acid (HA) and ε-polylysine (ε-PLL) to prepare a hydrogel with the ability to prevent wound infection and promote tissue regeneration. At the same time, using the macropore barrier effect of the lyophilized hydrogel scaffold, platelets in PRP are activated with calcium gluconate in the macropores of the scaffold carrier, and fibrinogen from PRP is converted in a fibrin-packed network forming a gel that interpenetrates the hydrogel scaffold carrier, thus creating a double network hydrogel with slow-release of growth factors from degranulated platelets. The hydrogel not only showed better performance in functional assays in vitro, but also showed more superior therapeutic effects in reducing inflammatory response, promoting collagen deposition, facilitating re-epithelialization and angiogenesis in the treatment of full skin defects in diabetic rats.

Protective Actions in Apical Periodontitis: The Regenerative Bioactivities Led by Mesenchymal Stem Cells

Resulting from bacterial infection, apical periodontitis (AP) is a common inflammatory disease of the periapical region of the tooth. The regeneration of the destroyed periapical alveolar bone and the surrounding periodontium tissues has long been a difficult task in clinical practice. These lesions are closely related to pathogen invasion and an overreactive immune response. It is worth noting that the protective healing process occurs simultaneously, in which mesenchymal stem cells (MSCs) have a crucial function in mediating the immune system and promoting regeneration. Here, we review the recent studies related to AP, with a focus on the regulatory network of MSCs. We also discuss the potential therapeutic approaches of MSCs in inflammatory diseases to provide a basis for promoting tissue regeneration and modulating inflammation in AP. A deeper understanding of the protective action of MSCs and the regulatory networks will help to delineate the underlying mechanisms of AP and pave the way for stem-cell-based regenerative medicine in the future.