Prospect of stem cells conditioned medium (secretome) in ligament and tendon healing: A systematic review

Equine Musculoskeletal Pathologies: Clinical Approaches and Therapeutical Perspectives-A Review

Musculoskeletal injuries such as equine osteoarthritis, osteoarticular defects, tendonitis/desmitis, and muscular disorders are prevalent among sport horses, with a fair prognosis for returning to exercise or previous performance levels. The field of equine medicine has witnessed rapid and fruitful development, resulting in a diverse range of therapeutic options for musculoskeletal problems. Staying abreast of these advancements can be challenging, prompting the need for a comprehensive review of commonly used and recent treatments. The aim is to compile current therapeutic options for managing these injuries, spanning from simple to complex physiotherapy techniques, conservative treatments including steroidal and non-steroidal anti-inflammatory drugs, hyaluronic acid, polysulfated glycosaminoglycans, pentosan polysulfate, and polyacrylamides, to promising regenerative therapies such as hemoderivatives and stem cell-based therapies. Each therapeutic modality is scrutinized for its benefits, limitations, and potential synergistic actions to facilitate their most effective application for the intended healing/regeneration of the injured tissue/organ and subsequent patient recovery. While stem cell-based therapies have emerged as particularly promising for equine musculoskeletal injuries, a multidisciplinary approach is underscored throughout the discussion, emphasizing the importance of considering various therapeutic modalities in tandem.

Effects of adipose-derived mesenchymal stem cell conditioned medium on human tenocytes exposed to high glucose

Introduction

Diabetic tendinopathy is a common invalidating and challenging disease that may be treated using stem cells. However, the effects of adipose-derived mesenchymal stem cell conditioned medium (ASC-CM) in diabetic tendinopathy have never been explored.

Objectives

The present study evaluated the effects of ASC-CM on morphology, cell viability, structure, and scratch wound closure of human tenocytes (HTNC) exposed to high glucose (HG).

Design

Experimental study.

Methods

HTNC were exposed to HG (25 mM) for 7, 14 and 21 days with or without ASC-CM for the last 24 h. CM was collected from 4 × 105 ASCs, centrifuged for 10 min at 200 g and sterilized with 0.22 μm syringe filter.

Results

At 7 days, HG-HTNC had decreased cell viability [72 ± 2%, p < 0.01 versus normal glucose (NG)] compared to NG-HTNC (90 ± 5%). A further decrement was detected after 14 and 21 days (60 ± 4% and 60 ± 5%, both, p < 0.01 versus NG and p < 0.01 versus HG7). While NG-HTNC evidenced a normal fibroblast cell-like elongated morphology, HG-HTNC showed increased cell roundness. In contrast, HG-HTNC exposed to ASC-CM showed a significant increase in cell viability, an improved cell morphology and higher scratch wound closure at all HG time points. Moreover, the exposure to ASC-CM significantly increased thrombospondin 1 and transforming growth factor beta 1 (TGF-β1) content in HG-HTNC. The TGF-β1 elevation was paralleled by higher Collagen I and Vascular Endothelial Growth Factor in HG-HTNC.

Conclusion

ASC-CM may restore the natural morphology, cell viability and structure of HTNC, promoting their scratch wound closure through TGF-β1 increase.

Secretome Analysis: Reading Cellular Sign Language to Understand Intercellular Communication

A significant portion of mammalian proteomes is secreted to the extracellular space to fulfill crucial roles in cell-to-cell communication. To best recapitulate the intricate and multi-faceted crosstalk between cells in a live organism, there is an ever-increasing need for methods to study protein secretion in model systems that include multiple cell types. In addition, posttranslational modifications further expand the complexity and versatility of cellular communication. This review aims to summarize recent strategies and model systems that employ cellular coculture, chemical biology tools, protein enrichment, and proteomic methods to characterize the composition and function of cellular secretomes. This is all geared towards gaining better understanding of organismal biology in vivo mediated by secretory signaling.

Prospect of Exosome in Ligament Healing: A Systematical Review

Aim

The relationship between ligaments and bone is a complex and heterogeneous junction involving bone, mineralized fibro cartilage, non-mineralized fibro cartilage and ligaments. Mesenchymal stem cells (MSC) can be used in vivo to control inflammation and aid in tissue repair, according to studies. This review focused on using exosomes as an alternative to MSC, as a cell-free therapy for modulating the remodelling process.

Methods

To conduct a systematic review of the literature, the phrases "exosome" and "ligament" or "tendon" and "extracellular vesicle" and "stem cells" were used as the search keywords in PubMed (MEDLINE), OVID, the Cochrane Library, and Science Direct. From the literature, 73 studies in all were found. Six studies were included in this systematic review after full-text evaluation.

Results

Six included studies covered a range of MSC types, isolation techniques, animal models, and interventions. Biomechanical results consistently indicated the beneficial impact of conditioned media, vesicles, and exosomes on treating tendons and ligaments. Noteworthy findings were the reduction of inflammation by iMSC-IEVs, chondrocyte protection by iPSC-EVs (extracellular vesicles generated by inflammation-primed adipose-derived stem cells), osteolysis treatment using DPSC-sEVs (small extracellular vesicles derived from dental pulp stem cells), and the contribution of exosome-educated macrophages to ligament injury wound healing.

Conclusion

Exosomes may serve as a cell-free therapeutic substitute for modulating the remodelling process, particularly in ligament healing.

Recent advances in exosomal non-coding RNA-based therapeutic approaches for photoaging

BACKGROUND

Photoaging is a degenerative biological process that affects the quality of life. It is caused by environmental factors including ultraviolet radiation (UVR), deep skin burns, smoking, active oxygen, chemical substances, and trauma. Among them, UVR plays a vital role in the aging process.

AIM

With the continuous development of modern medicine, clinical researchers have investigated novel approaches to treat aging. In particular, mesenchymal stem cells (MSCs), non-coding RNAs are involved in various physiological processes have broad clinical application as they have the advantages of convenient samples, abundant sources, and avoidable ethical issues.

METHODS

This article reviews research progress on five types of stem cell, exosomes, non-coding RNA in the context of photoaging treatment: adipose-derived stem cell, human umbilical cord MSCs, epidermal progenitor cells, keratinocyte stem cells, and hair follicle stem cells (HFSCs). It also includes stem cell related exosomes and their non-coding RNA research.

RESULTS

The results have clinical guiding significance for prevention and control of the onset and development of photoaging. It is found that stem cells secrete cytokines, cell growth factors, non-coding RNA, exosomes and proteins to repair aging skin tissues and achieve skin rejuvenation. In particular, stem cell exosomes and non-coding RNA are found to have significant research potential, as they possess the benefits of their source cells without the disadvantages which include immune rejection and granuloma formation.

Allogeneic umbilical cord mesenchymal stem cell conditioned medium (secretome) for treating posterior cruciate ligament rupture: a prospective single-arm study

BACKGROUND

Outcomes of the current management of posterior cruciate ligament (PCL) rupture are still unsatisfactory. Recent literature demonstrated the efficacy of the paracrine action of mesenchymal stem cells (MSC) in ligament rupture healing. This study aimed to evaluate the outcome of arthroscopic administration of allogeneic umbilical cord-derived MSC (UC-MSC) conditioned medium (secretome) for the treatment of PCL rupture.

PATIENTS AND METHODS

This is a prospective study including 12 individuals with PCL rupture grade 1 or 2 who were performed arthroscopy and secretome administrations. The functional and radiologic outcome of the knee was examined one year following intervention.

RESULTS

Preoperatively, posterior drawer test revealed three cases of grade 2+ and nine cases of grade 1+, whereas the final follow-up revealed two cases of grade 2+ and ten cases of grade 1+ PCL rupture. At final follow-up, the mean scores for the IKDC, modified Cincinnati, and Lysholm were 90.58 ± 4.30, 90.90 ± 2.15, and 89.42 ± 3.16, respectively. The means of the serial hop tests were 90.33, 94.16, 93.66, and 95.33 for single, triple, crossover, and time hop tests, respectively. Five patients were able to resume competitive sport after an average of 25.8 weeks (25-38). The final MRI analysis revealed that six knees (50%) regained PCL continuity with low signal intensity, five knees (41.6%) returned near-normal PCL continuity, and one knee (8.3%) regained PCL continuity but with deformed outlines.

CONCLUSIONS

Short-term follow-up indicated that the secretome generated from allogenic UC-MSC produces excellent functional and radiographic results in grade I-II PCL rupture.

Mesenchymal stem cell secretome-loaded fibrin glue improves the healing of intestinal anastomosis

Anastomotic leakage is a serious complication following gastrointestinal surgery and one of the leading causes of patient mortality. Despite the significant clinical and economic burden, there are currently no reliable treatment options to improve the healing of intestinal anastomosis and subsequently prevent anastomotic leakage. Recently, the development of regenerative medicine has shown promise for improving anastomotic healing. Recent studies have illustrated that stem cell-derived secretome can enhance tissue regeneration without the safety and ethical limitations of stem cell transplantation. Herein, we developed a fibrin glue topical delivery system loaded with mesenchymal stem cells (MSCs)-derived secretome for controlled delivery of bioactive factors, and evaluated its application potential in improving the healing of intestinal anastomosis. Under in vitro conditions, the MSCs secretome significantly promoted cell proliferation viability in a dose-dependent manner and resulted in the controlled release of growth factors via fibrin glue delivery. We established a rat surgical anastomotic model and experimentally found that MSCs secretome-loaded fibrin glue enhanced anastomotic bursting pressure, increased granulation tissue formation and collagen deposition, and significantly promoted anastomotic healing. Mechanistically, fibrin glue accelerated cell proliferation, angiogenesis, and macrophage M2 polarization at the surgical anastomotic site by releasing bioactive factors in the secretome, and it also alleviated the inflammatory response and cell apoptosis at the anastomotic site. Our results demonstrated for the first time that MSCs-derived secretome could promote the healing of intestinal anastomosis. Considering the accessibility and safety of the cell-free secretome, we believed that secretome-loaded fibrin glue would be a cell-free therapy to accelerate the healing of intestinal anastomosis with great potential for clinical translation.

The roles and therapeutic potentialof mesenchymal stem/stromal cells and their extracellular vesicles in tendinopathies

Tendinopathies encompass a highly prevalent, multi-faceted spectrum of disorders, characterized by activity-related pain, compromised function, and propensity for an extended absence from sport and the workplace. The pathophysiology of tendinopathy continues to evolve. For decades, it has been related primarily to repetitive overload trauma but more recently, the onset of tendinopathy has been attributed to the tissue's failed attempt to heal after subclinical inflammatory and immune challenges (failed healing model). Conventional tendinopathy management produces only short-term symptomatic relief and often results in incomplete repair or healing leading to compromised tendon function. For this reason, there has been increased effort to develop therapeutics to overcome the tissue's failed healing response by targeting the cellular metaplasia and pro-inflammatory extra-cellular environment. On this basis, stem cell-based therapies have been proposed as an alternative therapeutic approach designed to modify the course of the various tendon pathologies. Mesenchymal stem/stromal cells (MSCs) are multipotent stem cells often referred to as "medicinal signaling cells" due to their immunomodulatory and anti-inflammatory properties that can produce a pro-regenerative microenvironment in pathological tendons. However, the adoption of MSCs into clinical practice has been limited by FDA regulations and perceived risk of adverse events upon infusion in vivo. The introduction of cell-free approaches, such as the extracellular vesicles of MSCs, has encouraged new perspectives for the treatment of tendinopathies, showing promising short-term results. In this article, we review the most recent advances in MSC-based and MSC-derived therapies for tendinopathies. Preclinical and clinical studies are included with comment on future directions of this rapidly developing therapeutic modality, including the importance of understanding tissue loading and its relationship to any treatment regimen.

The therapeutic capacity of bone marrow MSC-derived extracellular vesicles in Achilles tendon healing is passage dependent and indicated by specific glycans

The therapeutic potential of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) for various diseases and tissue repair is attracting attention. Here, EVs from conditioned medium of human bone marrow MSCs at passage 5 (P5) and 12 (P12) were analyzed using mouse Achilles tendon rupture model and lectin microarray. P5 MSC-EVs accelerated Achilles tendon healing compared with P12 MSC-EVs. Fucose-specific lectin TJA-II was indicated as a glycan marker for therapeutic MSC-EVs. The present study demonstrated that early passaged MSC-EVs promote Achilles tendon healing compared with senescent MSC-EVs. Glycans on MSC-EVs might provide useful tools to establish a quality control and isolation system for therapeutic MSC-EVs in regenerative medicine.

Pro-angiogenic potential of a functionalized hydrogel scaffold as a secretome delivery platform: An innovative strategy for cell homing-based dental pulp tissue engineering

Angiogenesis is a key process that provides a suitable environment for successful tissue engineering and is even more crucial in regenerative endodontic procedures, since the root canal anatomy limits the development of a vascular network supply. Thus, sustainable and accelerated vascularization of tissue-engineered dental pulp constructs remains a major challenge in cell homing approaches. This study aimed to functionalize a chitosan hydrogel scaffold (CS) as a platform loaded with secretomes of stem cells from human exfoliated deciduous teeth (SHEDs) and evaluate its bioactive function and pro-angiogenic properties. Initially, the CS was loaded with SHED secretomes (CS-S), and the release kinetics of several trophic factors were assessed. Proliferation and chemotaxis assays were performed to analyze the effect of functionalized scaffold on stem cells from apical papilla (SCAPs) and the angiogenic potential was analyzed through the Matrigel tube formation assay with co-cultured of human umbilical vein endothelial cells and SCAPs. SHEDs and SCAPs expressed typical levels of mesenchymal stem cell surface markers. CS-S was able to release the trophic factors in a sustained manner, but each factor has its own release kinetics. The CS-S group showed a significantly higher proliferation rate, accelerated the chemotaxis, and higher capacity to form vascular-like structures. CS-S provided a sustained and controlled release of trophic factors, which, in turn, improved proliferation, chemotaxis and all angiogenesis parameters in the co-culture. Thus, the functionalization of chitosan scaffolds loaded with secretomes is a promising platform for cell homing-based tissue engineering.

Case Report: Repeated Intralesional Injections of Autologous Mesenchymal Stem Cells Combined With Platelet-Rich Plasma for Superficial Digital Flexor Tendon Healing in a Show Jumping Horse

In the present case report a show jumping 10-year-old Sella Italiano gelding, presented with severe lameness, swelling and pain at palpation of the mid-metacarpal region of the left forelimb. Clinical and ultrasound examination diagnosed a chronic tendonitis of the central region of the superficial digital flexor tendon (SDFT). The lesion was a reoccurrence since it developed from a previously healed injury. The horse had to stop competing and was unresponsive to gold-standard treatments as Non-steroidal anti-inflammatory drugs (NSAIDs) and conservative management after 6 months of therapy. The animal was subjected to repeated intralesional injections of autologous adipose-derived mesenchymal stem cells (AD-MSCs) combined with autologous platelet-rich plasma (PRP). The combined treatment was administered twice in a 1-month interval. The healing process was assessed through clinical examination, ultrasound imaging and quantification of oxidative stress products and inflammatory mediators in blood plasma. After 2 weeks from first injection, a reduction of concentration of oxidative-derived products was observed, together with an increase of anti-inflammatory cytokines and pro-mitotic growth factors. These results were reflected clinically as the horse showed a reduction of lameness along with swelling and pain after 4 weeks. At the 1-year follow-up, the horse showed no signs of lameness and swelling. The ultrasonographic examination highlighted a compact fiber alignment with a normal echogenic tendon as observed in the sound contralateral limb. Moreover, the horse went back to the previous level of competition. Our results suggest the positive effects of a repeated intralesional injection of AD-MSCs and PRP for the treatment of a chronic tendonitis with long-term effects and an improvement for both equine quality of life and athletic performance.

Tendon Immune Regeneration: Insights on the Synergetic Role of Stem and Immune Cells during Tendon Regeneration

Tendon disorders represent a very common pathology in today’s population, and tendinopathies that account 30% of tendon-related injuries, affect yearly millions of people which in turn cause huge socioeconomic and health repercussions worldwide. Inflammation plays a prominent role in the development of tendon pathologies, and advances in understanding the underlying mechanisms during the inflammatory state have provided additional insights into its potential role in tendon disorders. Different cell compartments, in combination with secreted immune modulators, have shown to control and modulate the inflammatory response during tendinopathies. Stromal compartment represented by tenocytes has shown to display an important role in orchestrating the inflammatory response during tendon injuries due to the interplay they exhibit with the immune-sensing and infiltrating compartments, which belong to resident and recruited immune cells. The use of stem cells or their derived secretomes within the regenerative medicine field might represent synergic new therapeutical approaches that can be used to tune the reaction of immune cells within the damaged tissues. To this end, promising opportunities are headed to the stimulation of macrophages polarization towards anti-inflammatory phenotype together with the recruitment of stem cells, that possess immunomodulatory properties, able to infiltrate within the damaged tissues and improve tendinopathies resolution. Indeed, the comprehension of the interactions between tenocytes or stem cells with the immune cells might considerably modulate the immune reaction solving hence the inflammatory response and preventing fibrotic tissue formation. The purpose of this review is to compare the roles of distinct cell compartments during tendon homeostasis and injury. Furthermore, the role of immune cells in this field, as well as their interactions with stem cells and tenocytes during tendon regeneration, will be discussed to gain insights into new ways for dealing with tendinopathies.

Ligament/Tendon Culture under Hypoxic Conditions: A Systematic Review

The hypoxic environment is a substantial factor in maintenance, proliferation, and differentiation of the cell cultures. Low oxygen is known as a potent chondrogenesis stimulus in stem cells that is important for clinical application and engineering of functional cartilage. Hypoxia can potentially induce angiogenesis process by secretion of cytokines. This systematic review goal is to discover the effect of hypoxic condition on tendon/ ligament culture and the best oxygen level of hypoxia for in vitro and in vivo studies. We included 21 articles. A comprehensive review of this database confirms that the hypoxic condition is a substantial factor in the maintenance, proliferation, and differentiation of ligament/tendon cultures. Cell proliferation in the severe hypoxic (oxygen concentration of 1%) group at 24 h postcultivation was considered significant, but cell proliferation was markedly inhibited in the severe hypoxic group after 48 h.

First immunohistochemical evidence of human tendon repair following stem cell injection: A case report and review of literature

BACKGROUND

Current clinical treatment options for symptomatic, partial-thickness rotator cuff tear (sPTRCT) offer only limited potential for true tissue healing and improvement of clinical results. In animal models, injections of adult stem cells isolated from adipose tissue into tendon injuries evidenced histological regeneration of tendon tissue. However, it is unclear whether such beneficial effects could also be observed in a human tendon treated with fresh, uncultured, autologous, adipose derived regenerative cells (UA-ADRCs). A specific challenge in this regard is that UA-ADRCs cannot be labeled and, thus, not unequivocally identified in the host tissue. Therefore, histological regeneration of injured human tendons after injection of UA-ADRCs must be assessed using comprehensive, immunohistochemical and microscopic analysis of biopsies taken from the treated tendon a few weeks after injection of UA-ADRCs.

CASE SUMMARY

A 66-year-old patient suffered from sPTRCT affecting the right supraspinatus and infraspinatus tendon, caused by a bicycle accident. On day 18 post injury [day 16 post magnetic resonance imaging (MRI) examination] approximately 100 g of abdominal adipose tissue was harvested by liposuction, from which approximately 75 × 10⁶ UA-ADRCs were isolated within 2 h. Then, UA-ADRCs were injected (controlled by biplanar X-ray imaging) adjacent to the injured supraspinatus tendon immediately after isolation. Despite fast clinical recovery, a follow-up MRI examination 2.5 mo post treatment indicated the need for open revision of the injured infraspinatus tendon, which had not been treated with UA-ADRCs. During this operation, a biopsy was taken from the supraspinatus tendon at the position of the injury. A comprehensive, immunohistochemical and microscopic analysis of the biopsy (comprising 13 antibodies) was indicative of newly formed tendon tissue.

CONCLUSION

Injection of UA-ADRCs can result in regeneration of injured human tendons by formation of new tendon tissue.

Hepatocyte Growth Factor-Induced Tendon Stem Cell Conditioned Medium Promotes Healing of Injured Achilles Tendon

Tendon repair is a medical challenge. Our present study investigated the effectiveness of acellular therapy consisting of conditioned medium (CM) of tendon stem cells (TSCs) induced with hepatocyte growth factor (HGF) in promoting the healing of injured Achilles tendon in a rat model. Proteomic analysis of soluble substances in the CM was performed using an array chip, and bioinformatic analysis was carried out to evaluate interactions among the factors. The effects of CM on viability and migratory capacity of tendon fibroblasts derived from rats with ruptured Achilles tendon were evaluated with the Cell Counting Kit 8 and wound healing assay, respectively. The expression of extracellular matrix (ECM)-related protein was assessed by western blotting. Rats with Achilles tendon injury were treated with CM by local injection for 2 weeks, and the organization of tendon fibers at the lesion site was evaluated by hematoxylin and eosin and Masson's trichrome staining of tissue samples. The deposition and degradation of ECM proteins and the expression of inflammatory factors at the lesion site were evaluated by immunohistochemistry and immunofluorescence. Biomechanical testing was carried out on the injured tendons to assess functional recovery. There were 12 bioactive molecules in the CM, with HGF as the hub of the protein-protein interaction network. CM treatment enhanced the viability and migration of tendon fibroblasts, altered the expression of ECM proteins, promoted the organization of tendon fibers, suppressed inflammation and improved the biomechanics of the injured Achilles tendon. These results suggest that HGF stimulates the secretion of soluble secretory products by TSCs and CM promotes the repair and functional recovery of ruptured Achilles tendon. Thus, HGF-induced TSC CM has therapeutic potential for the treatment of tendinopathy.

Amnion-Derived Teno-Inductive Secretomes: A Novel Approach to Foster Tendon Differentiation and Regeneration in an Ovine Model

Regenerative medicine has greatly progressed, but tendon regeneration mechanisms and robust in vitro tendon differentiation protocols remain to be elucidated. Recently, tendon explant co-culture (CO) has been proposed as an in vitro model to recapitulate the microenvironment driving tendon development and regeneration. Here, we explored standardized protocols for production and storage of bioactive tendon-derived secretomes with an evaluation of their teno-inductive effects on ovine amniotic epithelial cells (AECs). Teno-inductive soluble factors were released in culture-conditioned media (CM) only in response to active communication between tendon explants and stem cells (CMCO). Unsuccessful tenogenic differentiation in AECs was noted when exposed to CM collected from tendon explants (CMFT) only, whereas CMCO upregulated SCXB, COL I and TNMD transcripts, in AECs, alongside stimulation of the development of mature 3D tendon-like structures enriched in TNMD and COL I extracellular matrix proteins. Furthermore, although the tenogenic effect on AECs was partially inhibited by freezing CMCO, this effect could be recovered by application of an in vivo-like physiological oxygen (2% O2) environment during AECs tenogenesis. Therefore, CMCO can be considered as a waste tissue product with the potential to be used for the development of regenerative bio-inspired devices to innovate tissue engineering application to tendon differentiation and healing.

Conditioned medium of human bone marrow-derived stem cells promotes tendon-bone healing of the rotator cuff in a rat model

Rotator cuff repair is a common surgery in sports medicine. During the surgery, torn tendon was re-fixed onto the bony surface. The majority of patients gain good results. However, re-tear occurs in some patients. The reason under this phenomenon is that the normal tendon-bone enthesis cannot be reconstructed. In order to strengthen the tendon-bone healing and promote enthesis regeneration, numerous manners are tested, among which stem cell related therapies are preferred. Stem cells, due to the ability of multi-lineage differentiation, are widely used in regenerative medicine. However, safety and ethics concerns limit its clinical use. Recent studies found that it is the secretome of stem cells that is biologically effective. On ground of this, we, in the current study, collected the conditioned medium of human bone marrow-derived stem cells (hBMSC-CM) and tested whether this acellular method could promote tendon-bone healing in a rat model of rotator cuff repair. By using histological, radiological, and biomechanical methods, we found that hBMSC-CM promoted tendon-bone healing of the rat rotator cuff. Then, we noticed that hBMSC-CM exerted an impact on macrophage polarization both in vivo and in vitro by inhibiting M1 phenotype and promoting M2 phenotype. Further, we proved that the benefit of hBMSC-CM on tendon-bone healing was related to its regulation on macrophage. Finally, we proved that, hBMSC-CM influenced macrophage polarization, which was, at least partially, related to Smad2/3 signaling pathway. Based on the experiments above, we confirmed the benefit of hBMSC-CM on tendon-bone healing, which relied on its immune-regulative property. Considering the accessibility and safety of acellular hBMSC-CM, we believe it is a promising candidate clinically for tendon-bone healing.

Incorporating regenerative medicine into rehabilitation programmes: a potential treatment for ankle sprain

Ankle sprain has a great effect on morbidity and complications of chronic diseases. Experts have come to a consensus where ankle sprain can be managed by rest, ice, compression and elevation, non-steroidal anti-inflammatory drugs, immobilisation, functional support such as the use of an ankle brace, exercise, surgery and other therapies that include physiotherapy modalities and acupuncture. However, the time required for healing is still relatively long in addition to post-operative complications. Because of the challenges and setbacks faced by interventions to manage ankle sprains and in view of the recent trend and development in the field of regenerative medicine, this article discusses future treatments focusing on a personalised and holistic approach for ankle sprain management. This narrative review provides a novel idea for incorporating regenerative medicine into conventional therapy as an intervention for ankle sprain based on theoretical concepts and available evidence on regenerative medicine involving ligament injuries.

Prospect of stem cells conditioned medium (secretome) in ligament and tendon healing: A systematic review

BACKGROUND

Tendon or ligament tears can decrease patients' quality of life. Many therapeutic interventions are available to treat such injuries. Mesenchymal stem cells (MSCs) have been shown to be effective in treating tendon or ligament tears; however, the use of stem cell-conditioned medium (CM) requires further investigation. This review focused on the use of stem cell CM as treatment for tendon or ligament tears.

METHODS

A systematic literature search was performed on PubMed (MEDLINE), OVID, EMBASE, the Cochrane Library, Scopus, Web of Science, and Science Direct with the terms conditioned media or conditioned medium or secretome or microvesicle or extracellular vesicle or exosome, and tendon or ligament as the search keywords. A total of 852 articles were reviewed. Five articles were identified as relevant for this systematic review.

RESULTS

Meta-analysis could not be performed because of the high heterogeneity of the reviewed studies; however, the results of this study support a positive effect of conditioned media in tendon and ligament treatment.

CONCLUSION

This review provides evidence of improvement in the tendon and ligament healing process with stem cell CM therapy in preclinical studies.