Cartilage regeneration by chondrogenic induced adult stem cells in osteoarthritic sheep model

Cell-based tissue engineered flexor tendon allograft: A canine in vivo study

This study aimed to compare the clinically established autologous extrasynovial tendon graft to a newly developed tissue-engineered allograft (Eng-allograft) in terms of functional outcomes following flexor tendon reconstruction in a canine model. The second and fifth flexor digitorum profundus (FDP) tendons from 16 dogs were transected and repaired in Zone II. After 6 weeks of cage activity, the repaired tendons were intentionally ruptured, creating a clinically relevant model for reconstruction. The re-ruptured FDP tendons were then reconstructed using either the clinically standard autologous extrasynovial tendon graft or the Eng-allograft, which had been revitalized with autologous bone marrow-derived mesenchymal stem cells (BMSCs) and synovialized using carbodiimide derivatized synovial fluid (cd-SYN). Following 12 weeks of postoperative rehabilitation, the functional outcomes of the surgical digits were evaluated. The Eng-allograft group exhibited improved digital function, including lower digit work of flexion and reduced adhesion status, while maintaining similar tendon gliding resistance compared to the autograft group. However, the failure load of both the distal and proximal host/graft conjunctions in the Eng-allograft group was significantly lower than that of the autograft group with higher graft rupture at the host-graft junction. In conclusion, the decellularized allogenic intrasynovial tendon, when revitalized BMSCs and synovialized with cd-SYN, demonstrates positive effects on digital function improvement and adhesion reduction. However, the healing at both proximal and distal graft/host junctions is far lower than the autograft. Further research is needed to enhance the healing capacity of allograft conjunctions, aiming to achieve a comparable level of healing seen with autografts.

Mechanobiological Strategies to Enhance Ovine (Ovis aries) Adipose-Derived Stem Cells Tendon Plasticity for Regenerative Medicine and Tissue Engineering Applications

Adipose-derived stem cells (ADSCs) hold promise for tendon repair, even if their tenogenic plasticity and underlying mechanisms remain only partially understood, particularly in cells derived from the ovine animal model. This study aimed to characterize oADSCs during in vitro expansion to validate their phenotypic properties pre-transplantation. Moreover, their tenogenic potential was assessed using two in vitro-validated approaches: (1) teno-inductive conditioned media (CM) derived from a co-culture between ovine amniotic stem cells and fetal tendon explants, and (2) short- (48 h) and long-term (14 days) seeding on highly aligned PLGA (ha-PLGA) electrospun scaffold. Our findings indicate that oADSCs can be expanded without senescence and can maintain the expression of stemness (Sox2, Oct4, Nanog) and mesenchymal (CD29, CD166, CD44, CD90) markers while remaining negative for hematopoietic (CD31, CD45) and MHC-II antigens. Of note, oADSCs' tendon differentiation potential greatly depended on the in vitro strategy. oADSCs exposed to CM significantly upregulated tendon-related genes (COL1, TNMD, THBS4) but failed to accumulate TNMD protein at 14 days of culture. Conversely, oADSCs seeded on ha-PLGA fleeces quickly upregulated the tendon-related genes (48 h) and in 14 days accumulated high levels of the TNMD protein into the cytoplasm of ADSCs, displaying a tenocyte-like morphology. This mechano-sensing cellular response involved a complete SOX9 downregulation accompanied by YAP activation, highlighting the efficacy of biophysical stimuli in promoting tenogenic differentiation. These findings underscore oADSCs' long-term self-renewal and tendon differentiative potential, thus opening their use in a preclinical setting to develop innovative stem cell-based and tissue engineering protocols for tendon regeneration, applied to the veterinary field.

Unraveling the path to osteoarthritis management: targeting chondrocyte apoptosis for therapeutic intervention

Osteoarthritis (OA) is a chronic disease affecting joints and further causing disabilities. This disease affects around 240 million people worldwide. It is a multifactorial disease, and its etiology is difficult to determine. Although numerous therapeutic strategies are available, the therapies are aimed at reducing pain and improving patients' quality of life. Hence, there is an urgent need to develop disease-modifying drugs (DMOAD) that can reverse or halt OA progression. Apoptosis is a cell removal process that is important in maintaining homeostatic mechanisms in the development and sustaining cell population. The apoptosis of chondrocytes is believed to play an important role in OA progression due to poor chondrocytes self-repair abilities to maintain the extracellular matrix (ECM). Hence, targeting chondrocyte apoptosis can be one of the potential therapeutic strategies in OA management. There are various mediators and targets available to inhibit apoptosis such as autophagy, endoplasmic reticulum (ER) stress, oxidative stress, and inflammation. As such, this review highlights the importance and potential targets that can be aimed to reduce chondrocyte apoptosis.

A Simple and Effective Mechanical Method for Adipose-Derived Stromal Vascular Fraction Isolation

Over the last decades, there has been ongoing and evolving research concerning regenerative medicine, specifically, stem cells. The most common source of adult mesenchymal stem cells (MSCs) remains the adipose tissue and the easiest way to obtain such tissue is lipoaspirate. The fatty tissue obtained can be processed either in an enzymatic way, which is time-consuming and expensive and carries several dangers for the viability of the stem cells included, or with mechanical means which are fast, inexpensive, yield enough viable cells, and can be readily used for autologous transplantation in one-stage procedures. Herein, we demonstrate our non-enzymatic method for obtaining adipose-derived stromal vascular fraction comprising MSCs. The stromal vascular fraction was isolated via centrifugation, and the characteristics and numbers of the cells isolated have been tested with flow cytometry assay, cell culture, and differentiation. Over 91% of viable MSCs were isolated using the mechanical method. The cells retained the ability to differentiate into osteocytes, adipocytes, and chondrocytes. The method presented is simple, requiring no special equipment, and yields a viable population of stem cells in large numbers. These cells can be readily used in several operations (orthopedic, dentistry, fistulas, etc.) making feasible "one-stage" procedures, thus proving their benefits for the patient and the health care system.

Protecting the regenerative environment: selecting the optimal delivery vehicle for cartilage repair-a narrative review

Focal cartilage defects are common in youth and older adults, cause significant morbidity and constitute a major risk factor for developing osteoarthritis (OA). OA is the most common musculoskeletal (MSK) disease worldwide, resulting in pain, stiffness, loss of function, and is currently irreversible. Research into the optimal regenerative approach and methods in the setting of either focal cartilage defects and/or OA holds to the ideal of resolving both diseases. The two fundamentals required for cartilage regenerative treatment are 1) the biological element contributing to the regeneration (e.g., direct application of stem cells, or of an exogenous secretome), and 2) the vehicle by which the biological element is suspended and delivered. The vehicle provides support to the regenerative process by providing a protective environment, a structure that allows cell adherence and migration, and a source of growth and regenerative factors that can activate and sustain regeneration. Models of cartilage diseases include osteochondral defect (OCD) (which usually involve one focal lesion), or OA (which involves a more diffuse articular cartilage loss). Given the differing nature of these models, the optimal regenerative strategy to treat different cartilage diseases may not be universal. This could potentially impact the translatability of a successful approach in one condition to that of the other. An analogy would be the repair of a pothole (OCD) versus repaving the entire road (OA). In this narrative review, we explore the existing literature evaluating cartilage regeneration approaches for OCD and OA in animal then in human studies and the vehicles used for each of these two conditions. We then highlight strengths and challenges faced by the different approaches presented and discuss what might constitute the optimal cartilage regenerative delivery vehicle for clinical cartilage regeneration.

Cell-based therapies have disease-modifying effects on osteoarthritis in animal models. A systematic review by the ESSKA Orthobiologic Initiative. Part 2: bone marrow-derived cell-based injectable therapies

PURPOSE

Aim of this systematic review was to determine if bone marrow-derived cell-based injectable therapies induce disease-modifying effects in joints affected by osteoarthritis (OA) in animal models.

METHODS

A systematic review was performed on three electronic databases (PubMed, Web of Science, Embase) according to PRISMA guidelines. A synthesis of the results was performed investigating disease-modifying effects in preclinical animal studies comparing injectable bone marrow-derived products with OA controls or other products, different formulations or injection intervals, and the combination with other products. The risk of bias was assessed according to the SYRCLE's tool.

RESULTS

Fifty-three studies were included (1819 animals) with an increasing publication trend over time. Expanded cells were used in 48 studies, point-of-care products in 3 studies, and both approaches were investigated in 2 studies. Among the 47 studies presenting results on the disease-modifying effects, 40 studies (85%) reported better results with bone marrow-derived products compared to OA controls, with positive findings evident in 14 out of 20 studies (70%) in macroscopic assessment, in 30 out of 41 studies (73%) in histological assessment, and in 10 out of 13 studies (77%) in immunohistochemical evaluations. Clinical evaluations showed positive results in 7 studies out of 9 (78%), positive imaging results in 11 studies out of 17 (65%), and positive biomarker results in 5 studies out of 10 (50%). While 36 out of 46 studies (78%) reported positive results at the cartilage level, only 3 out of 10 studies (30%) could detect positive changes at the synovial level. The risk of bias was low in 42% of items, unclear in 50%, and high in 8%.

CONCLUSION

This systematic review of preclinical studies demonstrated that intra-articular injections of bone marrow-derived products can induce disease-modifying effects in the treatment of OA, slowing down the progression of cartilage damage with benefits at macroscopic, histological, and immunohistochemical levels. Positive results have been also observed in terms of clinical and imaging findings, as well as in the modulation of inflammatory and cartilage biomarkers, while poor effects have been described on the synovial membrane. These findings are important to understand the potential of bone marrow-derived products and to guide further research to optimise their use in the clinical practice.

LEVEL OF EVIDENCE

II.

Cell-based therapies have disease-modifying effects on osteoarthritis in animal models. A systematic review by the ESSKA Orthobiologic Initiative. Part 1: adipose tissue-derived cell-based injectable therapies

PURPOSE

The aim of this systematic review was to determine if adipose tissue-derived cell-based injectable therapies can induce disease-modifying effects in joints affected by osteoarthritis (OA).

METHODS

A systematic review was performed on three electronic databases (PubMed, Web of Science, Embase) according to PRISMA guidelines. A synthesis of the results was performed investigating disease-modifying effects in preclinical studies comparing injectable adipose-derived products with OA controls or other products, different formulations or injection intervals, and the combination with other products. The risk of bias was assessed according to the SYRCLE's tool.

RESULTS

Seventy-one studies were included (2,086 animals) with an increasing publication trend over time. Expanded cells were used in 65 studies, 3 studies applied point of care products, and 3 studies investigated both approaches. Overall, 48 out of 51 studies (94%) reported better results with adipose-derived products compared to OA controls, with positive findings in 17 out of 20 studies (85%) in macroscopic, in 37 out of 40 studies (93%) in histological, and in 22 out of 23 studies (96%)  in immunohistochemical evaluations. Clinical and biomarker evaluations showed positive results in 14 studies out of 18 (78%) and 12 studies out of 14 (86%), while only 9 studies out of 17 (53%) of the imaging evaluations were able to detect differences versus controls. The risk of bias was low in 38% of items, unclear in 51%, and high in (11%).

CONCLUSION

The current preclinical models document consistent evidence of disease-modifying effects of adipose-derived cell-based therapies for the treatment of OA. The high heterogeneity of the published studies highlights the need for further targeted research to provide recommendations on the optimal methodologies for a more effective application of these injective therapies for the treatment of OA in clinical practice.

LEVEL OF EVIDENCE

II.

Comparative Efficacy of the Stromal-Vascular Fraction Cells of Lipoaspirate and Hyaluronic Acid in the Treatment of Gonarthrosis: Results of an Interim Analysis

The use of cell technologies, in particular the stromal-vascular fraction of adipose tissue, is a new direction in the treatment of osteoarthritis of the weight-bearing joints. Stromal-vascular fraction cells have anti-inflammatory and immunomodulatory effects and are able to differentiate into connective tissue cells, including cartilage, tendons, and ligaments. Our clinical study showed the safety and good tolerability of intra-articular administration of autologous stromal-vascular fraction cells in 16 patients with severe manifestations of osteoarthritis. Single administration of stromal-vascular fraction cells led to more pronounced and stable (up to 12 months) clinical improvement in the main symptoms of the disease, including pain and functional activity of the affected joints, in comparison with intra-articular injection of hyaluronic acid (10 patients of the comparison group).

Effect and Mechanism of siRNAs Targeting IL-1β/TNF-α Combined with BMSCs Transplantation in Ameliorating Rheumatoid Arthritis in Rats

Simple Summary

The study aimed to explore the effect and potential mechanisms of siRNAs targeting IL-1β/TNF-α combined with BMSCs transplantation in ameliorating RA in rats. Collagen-induced arthritis model rats were randomly treated with IL-1β/TNF-α siRNA, BMSCs and IL-1β/TNF-α siRNA + BMSCs for 28 days. Compared with PBS group, BMSCs, siRNA, siRNA + BMSCs treatment groups showed significant lower toe swelling value, the immobility time, the spleen index, serum contents of IL-1β and TNF-α. In addition, the DR-X results showed that the knee carton surface tended to smoothing without bone hyperplasia, suggesting that these three treatments were all able to successfully ameliorate RA symptoms. In addition, compared with PBS group, the protein expression of p-NF-κB-p65 was significantly reduced in the knee of siRNA + BMSCs rats. BMSCs labeled with BrdU were also found in the knee of rats. Moreover, the mRNA expression of IL-1β, TNF-α and NF-κB-P65 in spleen tissue of siRNA + BMSCs rats were all significantly inhibited. Our results demonstrated that IL-1β/TNF-α siRNA, BMSCs and IL-1β/TNF-α siRNA + BMSCs were able to ameliorate RA inflammation by inhibiting the activation of NF-κB signaling pathways and reducing the erosion of articular cartilage, and IL-1β/TNF-α siRNA + BMSCs treatment showed synergism effects. Our study provides a new idea for gene and stem cell therapy for RA.

Abstract

Background: Rheumatoid arthritis (RA) is an autoimmune disease. Bone marrow mesenchymal stem cells (BMSCs) have multilineage differentiation and anti-inflammatory potential, and small interfering RNAs (siRNAs) can inhibit the target gene expression, which make them suitable for ameliorating RA. The current study was aimed to explore the effect and potential mechanisms of siRNAs targeting IL-1β/TNF-α combined with BMSCs transplantation in ameliorating RA in rats. Methods: Collagen-induced arthritis (CIA) model rats were randomly divided into five groups: PBS (Model control group), methotrexate (Positive drug treatment group), BMSCs (BMSCs transplantation group), siRNA (IL-1β/TNF-α siRNAs injection group), siRNA + BMSCs (Both IL-1β/TNF-α siRNAs injection and BMSCs transplantation group). After treatment for 0, 7, 14, 21, 28 days, the ameliorating effect was comprehensively assessed through results of the body weight, toe swelling value, the immobility time of forced swimming, the serum concentrations of IL-1β and TNF-α, knee joint DR-X imaging and pathological analysis as well as of IL-1β, TNF-α and NF-κB mRNA expression in spleen tissue. Furthermore, the potential underlying mechanism involving the NF-κB signaling pathways was also explored. Results: Compared with the PBS group, BMSCs, siRNA, siRNA + BMSCs treatment groups showed significant lower toe swelling value, immobility time, spleen index, serum contents of IL-1β and TNF-α. In addition, the DR-X results showed that the knee carton surface tended to smoothing without bone hyperplasia, suggesting that these three treatments were all able to successfully ameliorate RA symptoms. In addition, compared with the PBS group, the protein expression of p-NF-κB-p65 was significantly reduced in the knees of siRNA + BMSCs rats. BMSCs labeled with BrdU were also found in the knees of rats. Moreover, the mRNA expression of IL-1β, TNF-α and NF-κB-P65 in spleen tissue of siRNA + BMSCs rats were all significantly inhibited. Conclusions: Our results demonstrated for the first time that siRNA + BMSCs was able to ameliorate RA inflammation by inhibiting the activation of NF-κB signaling pathways and reducing the erosion of articular cartilage, and siRNA + BMSCs treatment showed synergism effects in helping ameliorating the inflammation and cartilage repair of RA rats. Therefore, the results of our present study provide a new idea for gene and stem cell therapy for RA.

Updates on mesenchymal stem cell therapies for articular cartilage regeneration in large animal models

There is an unmet need for novel and efficacious therapeutics for regenerating injured articular cartilage in progressive osteoarthritis (OA) and/or trauma. Mesenchymal stem cells (MSCs) are particularly promising for their chondrogenic differentiation, local healing environment modulation, and tissue- and organism-specific activity; however, despite early in vivo success, MSCs require further investigation in highly-translatable models prior to disseminated clinical usage. Large animal models, such as canine, porcine, ruminant, and equine models, are particularly valuable for studying allogenic and xenogenic human MSCs in a human-like osteochondral microenvironment, and thus play a critical role in identifying promising approaches for subsequent clinical investigation. In this mini-review, we focus on [1] considerations for MSC-harnessing studies in each large animal model, [2] source tissues and organisms of MSCs for large animal studies, and [3] tissue engineering strategies for optimizing MSC-based cartilage regeneration in large animal models, with a focus on research published within the last 5 years. We also highlight the dearth of standard assessments and protocols regarding several crucial aspects of MSC-harnessing cartilage regeneration in large animal models, and call for further research to maximize the translatability of future MSC findings.

Neural, adipocyte and hepatic differentiation potential of primary and secondary hair follicle stem cells isolated from Arbas Cashmere goats

Background

Arbas Cashmere goats are excellent domestic breeds with high yields of wool and cashmere. Their wool and cashmere can bring huge benefits to the livestock industry. Our studies intend to more fully understand the biological characteristics of hair follicle stem cells (HFSCs) in order to further explore the mechanisms of wool and cashmere regular regeneration. And they have been increasingly considered as promising multipotent cells in regenerative medicine because of their capacity to self-renew and differentiate. However, many aspects of the specific growth characteristics and differentiation ability of HFSCs remain unknown. This study aimed to further explore the growth characteristics and pluripotency of primary hair follicle stem cells (PHFSCs) and secondary hair follicle stem cells (SHFCs).

Results

We obtained PHFSCs and SHFSCs from Arbas Cashmere goats using combined isolation and purification methods. The proliferation and vitality of the two types of HFSCs, as well as the growth patterns, were examined. HFSC-specific markers and genes related to pluripotency, were subsequently identified. The PHFSCs and SHFSCs of Arbas Cashmere goat have a typical cobblestone morphology. Moreover, the PHFSCs and SHFSCs express HFSC surface markers, including CD34, K14, K15, K19 and LGR5. We also identified pluripotency-associated gene expression, including SOX2, OCT4 and SOX9, in PHFSCs and SHFSCs. Finally, PHFSCs and SHFSCs displayed multipotent abilities. PHFSCs and SHFSCs can be directed to differentiate into adipocyte-like, neural-like, and hepatocyte-like cells.

Conclusions

In conclusion, this study confirmed that the biological characteristics and differentiation potential of PHFSCs and SHFSCs from Arbas Cashmere goats. These findings broaden and refine our knowledge of types and characteristics of adult stem cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03420-3.

Role of animal models in biomedical research: a review

The animal model deals with the species other than the human, as it can imitate the disease progression, its’ diagnosis as well as a treatment similar to human. Discovery of a drug and/or component, equipment, their toxicological studies, dose, side effects are in vivo studied for future use in humans considering its’ ethical issues. Here lies the importance of the animal model for its enormous use in biomedical research. Animal models have many facets that mimic various disease conditions in humans like systemic autoimmune diseases, rheumatoid arthritis, epilepsy, Alzheimer’s disease, cardiovascular diseases, Atherosclerosis, diabetes, etc., and many more. Besides, the model has tremendous importance in drug development, development of medical devices, tissue engineering, wound healing, and bone and cartilage regeneration studies, as a model in vascular surgeries as well as the model for vertebral disc regeneration surgery. Though, all the models have some advantages as well as challenges, but, present review has emphasized the importance of various small and large animal models in pharmaceutical drug development, transgenic animal models, models for medical device developments, studies for various human diseases, bone and cartilage regeneration model, diabetic and burn wound model as well as surgical models like vascular surgeries and surgeries for intervertebral disc degeneration considering all the ethical issues of that specific animal model. Despite, the process of using the animal model has facilitated researchers to carry out the researches that would have been impossible to accomplish in human considering the ethical prohibitions.

The Clinical Efficacy of Platelet-Rich Plasma versus Conventional Drug Injection in the Treatment of Knee Osteoarthritis: A Study Protocol for a Randomized Controlled Trial

Knee osteoarthritis is a common chronic degenerative joint disease in middle-aged and elderly people. Intra-articular injection for the treatment of knee osteoarthritis is a regularly utilized nonsurgical treatment in modern medicine. Hyaluronic acid (HA) and platelet-rich plasma (PRP) are two frequently employed intra-articular devices. Hyaluronic acid (HA) is an accepted nonsurgical treatment for symptomatic KOA, and platelet-rich plasma is a popular option in the treatment of KOA in recent years. The purpose of this research is to compare the efficacy and safety of intra-articular injection of platelet-rich plasma (PRP) versus hyaluronic acid (HA) on the pain score scale, knee function, and related inflammatory biomarkers in KOA patients using a clinical randomized controlled trial. Participants are being randomized into either the hyaluronic acid (HA) or into the platelet-rich plasma (PRP) group. All patients receive 4 weeks of treatment (once a week), and well-being support and quadriceps training (3 times a week). The primary outcomes are measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the visual analog scale (VAS). The secondary outcomes include the activities of daily living score, erythrocyte sedimentation rate, C-reactive protein testing, interleukin-6 levels, and X-ray examination. In order to monitor the occurrence of irregularities and abnormalities, patients are assessed at each visit, and restorative treatment is given if necessary. The results of this clinical trial will verify the efficacy of PRP and HA in the treatment of KOA and provide important evidence for the clinical treatment of KOA. The trial was enlisted at the Chinese Clinical Trial Registry on 26 September 2020 (ChiCTR2000038635).

Physical and natural cross-linking approaches on 3D gelatin microspheres for cartilage regeneration

The use of gelatin microspheres (GM) as a cell carrier has been extensively researched. One of its limitation is that it dissolves rapidly in aqueous settings, precluding its use for long-term cell propagation. This circumstance necessitates the use of cross-linking agents to circumvent the constraint. Thus, the current study examines two different methods of cross-linking and their effect on the microsphere's '"physicochemical and cartilage tissue regeneration capacity. Crosslinking was accomplished by physical [Dehydrothermal (DHT)] and natural (Genipin) cross-linking of the 3D gelatin microspheres (GM). We begin by comparing the microstructures of the scaffolds and their long-term resistance to degradation under physiological conditions (in isotonic solution, at 37 °C, pH = 7.4). Infrared spectroscopy indicated that the gelatin structure was preserved after the cross-linking treatments. The cross-linked GM" 'demonstrated good cell adhesion, viability, proliferation, and widespread 3D scaffold colonization when seeded with human bone marrow mesenchymal stem cells (BMSCs). Additionally, the cross-linked microspheres enhanced chondrogenesis, as demonstrated by the data. It was discovered that cross-linked GM increased the expression of cartilage-related genes and the biosynthesis of a glycosaminoglycan-positive matrix as compared to non-crosslinked GM. In comparison, DHT-crosslinked results were significantly enhanced. To summarize, DHT treatment was found to be a superior approach for cross-linking the GM in order to promote better cartilage tissue regeneration.

Magnetic exposure using Samarium Cobalt (SmCO5) increased proliferation and stemness of human Umbilical Cord Mesenchymal Stem Cells (hUC-MSCs)

Despite the extensive reports on the potential hazard of magnetic field (MF) exposures on humans, there are also concurrently reported on the improved proliferative property of stem cells at optimum exposure. However, the effect on mesenchymal stem cells (MSCs) remains unknown. Therefore, we aimed to investigate the impact of induced static MF (SMF) on human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) using Samarium Cobalt (SmCO5). At passage 3, hUC-MSCs (1 × 10⁴) were exposed to 21.6 mT SMF by a direct exposure (DE) showed a significantly higher cell count (p < 0.05) in the growth kinetics assays with the shortest population doubling time relative to indirect exposure and negative control. The DE group was committed into the cell cycle with increased S phase (55.18 ± 1.38%) and G2/M phase (21.75 ± 1.38%) relative to the NC group [S-phase (13.54 ± 2.73%); G2/M phase (8.36 ± 0.28%)]. Although no significant changes were observed in the immunophenotype, the DE group showed an elevated expression of pluripotency-associated markers (OCT4, SOX2, NANOG, and REX1). These results suggest that the MFs could potentially induce proliferation of MSCs, a promising approach to promote stem cells propagation for clinical therapy and research without compromising the stemness of hUC-MSCs.

Comparison of the Infant and Adult Adipose-Derived Mesenchymal Stem Cells in Proliferation, Senescence, Anti-oxidative Ability and Differentiation Potential

BACKGROUND

Infant adipose-derived mesenchymal stem cells (ADSCs) collected from excised polydactyly fat tissue, which was surgical waste, could be cultured and expanded in vitro in this study. In addition, the collecting process would not cause pain in the host. In this study, the proliferation, reduction of senescence, anti-oxidative ability, and differentiation potential in the infant ADSCs were compared with those in the adult ADSCs harvested from thigh liposuction to determine the availability of infant ADSCs.

METHODS

Proliferation was determined by detecting the fold changes in cell numbers and doubling time periods. Senescence was analyzed by investigating the age-related gene expression levels and the replicative stress. The superoxide dismutase (SOD) gene expression, adipogenic, neurogenic, osteogenic, and tenogenic differentiation were compared by RT-qPCR. The chondrogenic differentiation efficiency was also determined using RT-qPCR and immunohistochemical staining.

RESULTS

The proliferation, SOD (SOD1, SOD2 and SOD3) gene expression, the stemness-related gene (c-MYC) and telomerase reverse transcriptase of the infant ADSCs at early passages were enhanced compared with those of the adults'. Cellular senescence related genes, including p16, p21 and p53, and replicative stress were reduced in the infant ADSCs. The adipogenic genes (PPARγ and LPL) and neurogenic genes (MAP2 and NEFH) of the infant ADSC differentiated cells were significantly higher than those of the adults' while the expression of the osteogenic genes (OCN and RUNX) and tenogenic genes (TNC and COL3A1) of both demonstrated opposite results. The chondrogenic markers (SOX9, COL2 and COL10) were enhanced in the infant ADSC differentiated chondrogenic pellets, and the expression levels of SODs were decreased during the differentiation process.

CONCLUSION

Cultured infant ADSCs demonstrate less cellular senescence and replicative stress, higher proliferation rates, better antioxidant defense activity, and higher potential of chondrogenic, adipogenic and neurogenic differentiation.

Preclinical studies and clinical trials on mesenchymal stem cell therapy for knee osteoarthritis: A systematic review on models and cell doses

AIM

To provide a systematic analysis of the study design in knee osteoarthritis (OA) preclinical studies, focusing on the characteristics of animal models and cell doses, and to compare these to the characteristics of clinical trials using mesenchymal stem cells (MSCs) for the treatment of knee OA.

METHOD

A systematic and comprehensive search was conducted using the PubMed, Web of Science, Ovid, and Embase electronic databases for research papers published in 2009-2020 on testing MSC treatment in OA animal models. The PubMed database and ClinicalTrials.gov website were used to search for published studies reporting clinical trials of MSC therapy for knee OA.

RESULTS

In total, 9234 articles and two additional records were retrieved, of which 120 studies comprising preclinical and clinical studies were included for analysis. Among the preclinical studies, rats were the most commonly used species for modeling knee OA, and anterior cruciate ligament transection was the most commonly used method for inducing OA. There was a correlation between the cell dose and body weight of the animal. In clinical trials, there was large variation in the dose of MSCs used to treat knee OA, ranging from 1 × 10⁶ to 200 × 10⁶ cells with an average of 37.91 × 10⁶ cells.

CONCLUSION

Mesenchymal stem cells have shown great potential in improving pain relief and tissue protection in both preclinical and clinical studies of knee OA. Further high-quality preclinical and clinical studies are needed to explore the dose effectiveness relationship of MSC therapy and to translate the findings from preclinical studies to humans.

Regenerative Engineering Animal Models for Knee Osteoarthritis

Abstract

Osteoarthritis (OA) of the knee is the most common synovial joint disorder worldwide, with a growing incidence due to increasing rates of obesity and an aging population. A significant amount of research is currently being conducted to further our understanding of the pathophysiology of knee osteoarthritis to design less invasive and more effective treatment options once conservative management has failed. Regenerative engineering techniques have shown promising preclinical results in treating OA due to their innovative approaches and have emerged as a popular area of study. To investigate these therapeutics, animal models of OA have been used in preclinical trials. There are various mechanisms by which OA can be induced in the knee/stifle of animals that are classified by the etiology of the OA that they are designed to recapitulate. Thus, it is essential to utilize the correct animal model in studies that are investigating regenerative engineering techniques for proper translation of efficacy into clinical trials. This review discusses the various animal models of OA that may be used in preclinical regenerative engineering trials and the corresponding classification system.

Lay Summary

Osteoarthritis (OA) of the knee is the most common synovial joint disease worldwide, with high rates of occurrence due to an increase in obesity and an aging population. A great deal of research is currently underway to further our understanding of the causes of osteoarthritis, to design more effective treatments. The emergence of regenerative engineering has provided physicians and investigators with unique opportunities to join ideas in tackling human diseases such as OA. Once the concept is proven to work, the initial procedure for the evaluation of a treatment solution begins with an animal model. Thus, it is essential to utilize a suitable animal model that reflects the particular ailment in regenerative engineering studies for proper translation to human patients as each model has associated advantages and disadvantages. There are various ways by which OA can occur in the knee joint, which are classified according to the particular cause of the OA. This review discusses the various animal models of OA that may be used in preclinical regenerative engineering investigations and the corresponding classification system.

Type II Collagen-Conjugated Mesenchymal Stem Cells Micromass for Articular Tissue Targeting

The tissue engineering approach in osteoarthritic cell therapy often requires the delivery of a substantially high cell number due to the low engraftment efficiency as a result of low affinity binding of implanted cells to the targeted tissue. A modification towards the cell membrane that provides specific epitope for antibody binding to a target tissue may be a plausible solution to increase engraftment. In this study, we intercalated palmitated protein G (PPG) with mesenchymal stem cells (MSCs) and antibody, and evaluated their effects on the properties of MSCs either in monolayer state or in a 3D culture state (gelatin microsphere, GM). Bone marrow MSCs were intercalated with PPG (PPG-MSCs), followed by coating with type II collagen antibody (PPG-MSC-Ab). The effect of PPG and antibody conjugation on the MSC proliferation and multilineage differentiation capabilities both in monolayer and GM cultures was evaluated. PPG did not affect MSC proliferation and differentiation either in monolayer or 3D culture. The PPG-MSCs were successfully conjugated with the type II collagen antibody. Both PPG-MSCs with and without antibody conjugation did not alter MSC proliferation, stemness, and the collagen, aggrecan, and sGAG expression profiles. Assessment of the osteochondral defect explant revealed that the PPG-MSC-Ab micromass was able to attach within 48 h onto the osteochondral surface. Antibody-conjugated MSCs in GM culture is a potential method for targeted delivery of MSCs in future therapy of cartilage defects and osteoarthritis.

Effects of Normal Synovial Fluid and Interferon Gamma on Chondrogenic Capability and Immunomodulatory Potential Respectively on Equine Mesenchymal Stem Cells

Synovial fluid contains cytokines, growth factors and resident mesenchymal stem cells (MSCs). The present study aimed to (1) determine the effects of autologous and allogeneic synovial fluid on viability, proliferation and chondrogenesis of equine bone marrow MSCs (BMMSCs) and (2) compare the immunomodulatory properties of equine synovial fluid MSCs (SFMSCs) and BMMSCs after stimulation with interferon gamma (INF-γ). To meet the first aim of the study, the proliferation and viability of MSCs were evaluated by MTS and calcein AM staining assays. To induce chondrogenesis, MSCs were cultured in a medium containing TGF-β1 or different concentrations of synovial fluid. To meet the second aim, SFMSCs and BMMSCs were stimulated with IFN-γ. The concentration of indoleamine-2,3-dioxygenase (IDO) and nitric oxide (NO) were examined. Our results show that MSCs cultured in autologous or allogeneic synovial fluid could maintain proliferation and viability activities. Synovial fluid affected chondrocyte differentiation significantly, as indicated by increased glycosaminoglycan contents, compared to the chondrogenic medium containing 5 ng/mL TGF-β1. After culturing with IFN-γ, the conditioned media of both BMMSCs and SFMSCs showed increased concentrations of IDO, but not NO. Stimulating MSCs with synovial fluid or IFN-γ could enhance chondrogenesis and anti-inflammatory activity, respectively, suggesting that the joint environment is suitable for chondrogenesis.

A Prospective Study Comparing Leukocyte-Poor Platelet-Rich Plasma Combined with Hyaluronic Acid and Autologous Microfragmented Adipose Tissue in Patients with Early Knee Osteoarthritis

The objective of this study was to compare the clinical efficacy of repeated doses of leucocyte-poor platelet-rich plasma (LP-PRP) plus hyaluronic acid (HA) to a single dose of autologous microfragmented adipose tissue (AMAT) injections in patients with early osteoarthritis (OA) symptoms. Eighty knees in 50 patients (mean age: 61.3 years) were randomly allocated into two equal groups in a nonblinded design and prospectively followed for 12 months. Group 1 received three intra-articular injections (1 month apart) using autologous LP-PRP+HA. Group 2 received a single dose of AMAT injection. Outcomes were measured by PROMs Tegner, Marx, visual analog scale, and Knee Injury and Osteoarthritis Outcome Score (KOOS) at 6 and 12 months. Both groups had significant clinical and functional improvement at 6 and 12 months. The differences between groups were statistically significant in Tegner score and KOOS symptoms (both P < 0.05) at 6 months in group 2. The test with statistically significant differences (P < 0.05) at 12 months was Tegner (P < 0.001), with group 2 having a higher median than group 1. LP-PRP+HA and AMAT lead to clinical and functional improvement at 6 and 12 months. AMAT showed better clinical results in Tegner and KOOS symptoms at 6 months and Tegner at 12 months. Understanding which therapy offers the most benefits with the least risk can significantly improve the quality of life for millions of people affected by OA. Long-term randomized controlled studies are needed to verify differences in efficacy.

Adipose Derived Mesenchymal Stem Cells from a Hypoxic Culture Reduce Cartilage Damage

The method to benifit tissue engineering of adipose-derived stem cells (ADSCs) to cartilage has been an objective of intense research in treating increasing cartilage-related disease. In this study, whether hypoxic expansion would enhance the proliferation and in vitro chondrogenic differentiation of ADSCs was studied, and then hypoxic expansion was applied to reduce cartilage damage in a rat model in vivo. Hypoxic expansion increased the proliferation and decreased the expression of aging-related genes, including p16, p21, and p53, of human ADSCs in comparison with normoxic expansion. In addition, the γH2AX expression was reduced in the hypoxic ADSCs. The chondrogenic markers were enhanced in the hypoxic ADSC differentiated chondrogenic pellets, including SOX9 on day 7 and gene expressions of COL 2 and COL 10 on day 21. To determine the in vitro chondrogenic differentiation potential of ADSCs, ADSC differentiated 21-day chondrogenic pellets were stained by Alcian blue staining and the immunostaining of COL 2 and COL 10, the results of which confirmed the enhancement of differentiation potential after the hypoxic expansion. Moreover, cartilage injury in a rat model was reduced by hypoxic ADSC treatment that was determined by histological and immunohistochemical staining detections. The effects of hypoxic expansion of ADSCs and bone marrow-derived stem cells (BMSCs) on chondrogenic differentiation potential were also compared. Smaller sizes were presented in the in vitro hypoxic BMSC differentiated chondrogenic pellets, whereas the chondrogenic marker expressions were significantly higher than those of the hypoxic ADSCs. However, there was no significant difference between the treatments of the hypoxic ADSCs and BMSCs in the cartilage injury in vivo. In conclusion, hypoxic expansion increases the chondrogenic differentiation potential of ADSCs and BMSCs in vitro and enhances them to reduce cartilage damage in vivo. Although the hypoxic BMSCs showed compact chondrogenic pellet formation and higher potential of chondrogenesis, the easy access and large resources of ADSCs still uplifted the application.

Recent Developed Strategies for Enhancing Chondrogenic Differentiation of MSC: Impact on MSC-Based Therapy for Cartilage Regeneration

Articular cartilage is susceptible to damage, but its self-repair is hindered by its avascular nature. Traditional treatment methods are not able to achieve satisfactory repair effects, and the development of tissue engineering techniques has shed new light on cartilage regeneration. Mesenchymal stem cells (MSCs) are one of the most commonly used seed cells in cartilage tissue engineering. However, MSCs tend to lose their multipotency, and the composition and structure of cartilage-like tissues formed by MSCs are far from those of native cartilage. Thus, there is an urgent need to develop strategies that promote MSC chondrogenic differentiation to give rise to durable and phenotypically correct regenerated cartilage. This review provides an overview of recent advances in enhancement strategies for MSC chondrogenic differentiation, including optimization of bioactive factors, culture conditions, cell type selection, coculture, gene editing, scaffolds, and physical stimulation. This review will aid the further understanding of the MSC chondrogenic differentiation process and enable improvement of MSC-based cartilage tissue engineering.

Two-year clinical outcomes of autologous microfragmented adipose tissue in elderly patients with knee osteoarthritis: a multi-centric, international study

PURPOSE

The aim of this study is to evaluate the outcomes of autologous microfragmented adipose tissue (MFAT) injection in elderly patients with knee osteoarthritis (OA). We hypothesized that MFAT knee infiltration for the treatment of knee OA would yield good clinical results out to two years follow-up.

METHODS

Multi-centric, international, open-label study conducted by orthopedic surgery, and/or regenerative medicine facilities utilizing patient registries. Subjects recruited for eligibility. The primary outcome measure was Knee Injury and Osteoarthritis Outcome Score (KOOS). Outcomes and patient factors were compared to baseline, at six, 12, and 24 months. Statistical models were used to assess KOOS subscores and probability of exceeding the Minimally Clinically Important Difference (MCID) or Patient Acceptable Symptom State (PASS), and to assess the effect of the treatment variables on KOOS - Pain.

RESULTS

Seventy-five patients, 120 primary treatments, mean age 69.6 years, (95%CI 68.3-70.9), BMI 28.4 (95%CI 27.3-29.6), with KL grade 2 to 4 knee OA treated with a single MFAT injection. KL grades 2 (15.1%), 3 (56.3%), and 4 (28.6%), with 20.8% of knees having previously undergone surgery. Patients with KL grade 2 disease had the best results in KOOS - Pain (P = 0.001), at six, 12, and 24 months. Including advanced KL grade 3 and 4 osteoarthritis patients, significant functional and quality of life success was seen in 106/120 treatments (88.3%, 66 patients) at all follow-up time points. Fourteen treatments (11.7%, 9 patients) failed prior to the study endpoint.

CONCLUSION

This study shows that a single-dose MFAT injection leads to clinical, functional, and quality of life improvement at two years in elderly patients, in KL grades 2 to 4 of knee osteoarthritis. These findings provide evidence that this treatment modality could be a safe and effective option to other commonly available treatments in carefully selected patients.

A brief very-low oxygen tension regimen is sufficient for the early chondrogenic commitment of human adipose-derived mesenchymal stem cells

PURPOSE

The aim of this study was to evaluate the effects exerted over chondrogenic commitment of human adipose-derived mesenchymal stem cells (ADSCs) by a very low oxygen tension (<1% pO₂).

MATERIALS/METHODS

Cell morphology, mRNA levels of chondrocyte-specific marker genes and the involvement of p38 MAPK signalling were monitored in human ADSCs under a very low oxygen tension.

RESULTS

Cell morphology was significantly changed after two days of hypoxic preconditioning when they featured as elongated spindle-shaped cells. SRY-box containing gene 9, aggrecan and collagen type II mRNA levels were enhanced under severe hypoxic culture conditions. Moreover, the inhibition of p38 MAPK resulted in a substantial reduction in transcription of the above-mentioned specific genes, proving the pivotal role of this pathway in the transcriptional regulation of chondrogenesis.

CONCLUSIONS

Here, we propose a protocol showing the early commitment of stem cells towards the chondrogenic phenotype in only 2 days of culture via a very low hypoxic environment, in the absence of growth factors added in the culture medium.

Intra-articular injection of human synovium-derived mesenchymal stem cells in beagles with surgery-induced osteoarthritis

BACKGROUND

Recently, cell-based tissue engineering approaches using mesenchymal stem cells (MSCs) have been used to treat osteoarthritis (OA). However, the efficacy of human synovium-derived MSCs (hSD-MSCs) has not yet been tested in a canine model of OA. The purpose of this study was to investigate the therapeutic effects of intra-articular hSD-MSC injections in a canine OA model.

METHODS

Sixty beagles underwent surgical manipulation to induce OA and received intra-articular injection 4 weeks after surgery. The dogs were divided into five groups (n = 12) according to the injection material: G1, sham group; G2, control group injected with phosphate-buffered saline; G3, G4, and G5, experimental groups injected with different hSD-MSC dosages (G3, 2.4 × 10⁶ cells; G4, 4.8 × 10⁶ cells; G5, 9.6 × 10⁶ cells). Magnetic resonance imaging (MRI) and histopathological and immunohistochemical examinations were performed 6 and 24 weeks after injection.

RESULTS

MRI revealed significant improvements in synovitis 24 weeks after injection in the hSD-MSC-injected groups (G3-G5). Histopathologic analyses showed that cartilage structure and proteoglycan staining were also significantly improved in these groups (G3-G5) 6 weeks after injection and improved further after 24 weeks. Immunohistochemical analysis revealed significant differences in the levels of collagen types I and II between the hSD-injected groups (G3-G5), indicating a similar extracellular matrix (ECM) composition to naïve articular cartilage.

CONCLUSION

Our study demonstrated for the first time that intra-articular hSD-MSC injection ameliorates the progression of canine OA by restoring cartilage, promoting ECM synthesis, and inhibiting the inflammatory response.

Pathophysiological Perspective of Osteoarthritis

Osteoarthritis (OA) is the most well-known degenerative disease among the geriatric and is a main cause of significant disability in daily living. It has a multifactorial etiology and is characterized by pathological changes in the knee joint structure including cartilage erosion, synovial inflammation, and subchondral sclerosis with osteophyte formation. To date, no efficient treatment is capable of altering the pathological progression of OA, and current therapy is broadly divided into pharmacological and nonpharmacological measures prior to surgical intervention. In this review, the significant risk factors and mediators, such as cytokines, proteolytic enzymes, and nitric oxide, that trigger the loss of the normal homeostasis and structural changes in the articular cartilage during the progression of OA are described. As the understanding of the mechanisms underlying OA improves, treatments are being developed that target specific mediators thought to promote the cartilage destruction that results from imbalanced catabolic and anabolic activity in the joint.

A Translational Porcine Model for Human Cell-Based Therapies in the Treatment of Posttraumatic Osteoarthritis After Anterior Cruciate Ligament Injury

BACKGROUND

There is a high incidence of posttraumatic osteoarthritis (PTOA) after anterior cruciate ligament (ACL) injury, and these injuries represent an enormous health care economic burden. In an effort to address this unmet clinical need, there has been increasing interest in cell-based therapies.

PURPOSE

To establish a translational large animal model of PTOA and demonstrate the feasibility of intra-articular human cell-based interventions.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Nine Yucatan mini-pigs underwent unilateral ACL transection and were monitored for up to 12 weeks after injury. Interleukin 1 beta (IL-1β) levels and collagen breakdown were evaluated longitudinally using enzyme-linked immunosorbent assays of synovial fluid, serum, and urine. Animals were euthanized at 4 weeks (n = 3) or 12 weeks (n = 3) after injury, and injured and uninjured limbs underwent magnetic resonance imaging (MRI) and histologic analysis. At 2 days after ACL injury, an additional 3 animals received an intra-articular injection of 10⁷ human bone marrow-derived mesenchymal stem cells (hBM-MSCs) combined with a fibrin carrier. These cells were labeled with the luciferase reporter gene (hBM-MSCs-Luc) as well as fluorescent markers and intracellular iron nanoparticles. These animals were euthanized on day 0 (n = 1) or day 14 (n = 2) after injection. hBM-MSC-Luc viability and localization were assessed using ex vivo bioluminescence imaging, fluorescence imaging, and MRI.

RESULTS

PTOA was detected as early as 4 weeks after injury. At 12 weeks after injury, osteoarthritis could be detected grossly as well as on histologic analysis. Synovial fluid analysis showed elevation of IL-1β shortly after ACL injury, with subsequent resolution by 2 weeks after injury. Collagen type II protein fragments were elevated in the synovial fluid and serum after injury. hBM-MSCs-Luc were detected immediately after injection and at 2 weeks after injection using fluorescence imaging, MRI, and bioluminescence imaging.

CONCLUSION

This study demonstrates the feasibility of reproducing the chondral changes, intra-articular cytokine alterations, and body fluid biomarker findings consistent with PTOA after ACL injury in a large animal model. Furthermore, we have demonstrated the ability of hBM-MSCs to survive and express transgene within the knee joint of porcine hosts without immunosuppression for at least 2 weeks.

CLINICAL RELEVANCE

This model holds great potential to significantly contribute to investigations focused on the development of cell-based therapies for human ACL injury-associated PTOA in the future (see Appendix Figure A1, available online).

Evaluation of cartilage biomechanics and knee joint microenvironment after different cell-based treatments in a sheep model of early osteoarthritis

PURPOSE

Aiming to prevent cartilage damage during early osteoarthritis (OA), the therapeutic challenge is to restore and maintain the physiological and functional properties of such a tissue with minimally invasive therapeutic strategies.

METHODS

Accordingly, an in vivo model of early OA in sheep was here treated through three different cell therapies (culture expanded ADSCs, SVF, and culture expanded AECs) thus to preserve the joint surface from the progression of the pathology. Three months after the treatment injections, their performance was assessed through mechanical automated mapping (Young's modulus and cartilage thickness), gross evaluation of articular surfaces, and biochemical analysis of the synovial fluid.

RESULTS

No severe degeneration was observed after three months from OA induction. Cartilage mechanical properties were crucial to identify early degeneration. All the treatments improved the macroscopic cartilage surface aspect and reduced pro-inflammatory cytokines in the synovial fluid. Among the three treatments, SVF highlighted the best performance while ADSCs the worst.

CONCLUSION

Despite that the evaluated experimental time is an early follow-up and, thus, longer trial is mandatory to properly assess treatments effectiveness, the proposed multidisciplinary approach allowed to obtain preliminary, but also crucial, results concerning the reduction in OA signs on cartilage properties, in osteophyte development and in all the inflammatory markers.

Human chondrocyte-conditioned medium promotes chondrogenesis of bone marrow stem cells

Background

Cell-based therapy for osteoarthritis requires culturing of good quality cells, especially with a chondrogenic lineage, for implantation.

Objective

To investigate the ability of chondrocyte-conditioned medium (CCM) to induced chondrogenesis.

Methods

Bone marrow mesenchymal stem cells (BMSCs) were subjected to chondrogenic induction using CCM and chondrocyte induction medium (CIM). The optimal condition for the collection of CCM was evaluated by quantifying the concentration of secreted proteins. The chondrogenic efficiency of BMSCs induced by CCM (iCCM) was evaluated using immunocytochemical analysis, Safranin-O staining, and gene expression.

Results

Protein quantification revealed that CCM obtained from cells at passage 3 at the 72 h collection point had the greatest amount of protein. Supplementation of CCM results in the aggregation of BMSCs; however, no clumping was visible as in iCIM. The expression of collagen type 2 was detected as early as day 7 for all groups except for non-induced BMSCs; however, the level of expression decreased with culture time. Similarly, all tested groups showed positive staining for Safranin-O as early as day 7. The induction of BMSCs by CCM caused the down-regulation of collagen type 1, along with the up-regulation of the collagen type 2, ACP and SOX9 genes.

Conclusion

The optimum CCM to induce BMSC into chondrocytes was collected at passage 3 after 72 h and was used in a 50:50 ratio of CCM to fresh medium.

Adipose-Derived Mesenchymal Stem Cell Treatments and Available Formulations

PURPOSE OF REVIEW

The use of human adipose-derived mesenchymal stem cells (ADSCs) has gained attention due to its potential to expedite healing and the ease of harvesting; however, clinical evidence is limited, and questions concerning optimal method of delivery and long-term outcomes remain unanswered.

RECENT FINDINGS

Administration of ADSCs in animal models has been reported to aid in improved healing benefits with enhanced repair biomechanics, superior gross histological appearance of injury sites, and higher concentrations of growth factors associated with healing compared to controls. Recently, an increasing body of research has sought to examine the effects of ADSCs in humans. Several available processing techniques and formulations for ADSCs exist with evidence to suggest benefits with the use of ADSCs, but the superiority of any one method is not clear. Evidence from the most recent clinical studies available demonstrates promising outcomes following treatment of select musculoskeletal pathologies with ADSCs despite reporting variability among ADSCs harvesting and processing; these include (1) healing benefits and pain improvement for rotator cuff and Achilles tendinopathies, (2) improvements in pain and function in those with knee and hip osteoarthritis, and (3) improved cartilage regeneration for osteochondral focal defects of the knee and talus. The limitation to most of this literature is the use of other therapeutic biologics in combination with ADSCs. Additionally, many studies lack control groups, making establishment of causation inappropriate. It is imperative to perform higher-quality studies using consistent, predictable control populations and to standardize formulations of ADSCs in these trials.

3D Culture of MSCs on a Gelatin Microsphere in a Dynamic Culture System Enhances Chondrogenesis

Recent advancement in cartilage tissue engineering has explored the potential of 3D culture to mimic the in vivo environment of human cartilaginous tissue. Three-dimensional culture using microspheres was described to play a role in driving the differentiation of mesenchymal stem cells to chondrocyte lineage. However, factors such as mechanical agitation on cell chondrogenesis during culture on the microspheres has yet to be elucidated. In this study, we compared the 2D and 3D culture of bone-marrow-derived mesenchymal stem cells (BMSCs) on gelatin microspheres (GMs) in terms of MSC stemness properties, immune-phenotype, multilineage differentiation properties, and proliferation rate. Then, to study the effect of mechanical agitation on chondrogenic differentiation in 3D culture, we cultured BMSCs on GM (BMSCs-GM) in either static or dynamic bioreactor system with two different mediums, i.e., F12: DMEM (1:1) + 10% FBS (FD) and chondrogenic induction medium (CIM). Our results show that BMSCs attached to the GM surface and remained viable in 3D culture. BMSCs-GM proliferated faster and displayed higher stemness properties than BMSCs on a tissue culture plate (BMSCs-TCP). GMs also enhanced the efficiency of in-vitro chondrogenesis of BMSCs, especially in a dynamic culture with higher cell proliferation, RNA expression, and protein expression compared to that in a static culture. To conclude, our results indicate that the 3D culture of BMSCs on gelatin microsphere was superior to 2D culture on a standard tissue culture plate. Furthermore, culturing BMSCs on GM in dynamic culture conditions enhanced their chondrogenic differentiation.

The use of large animals to facilitate the process of MSC going from laboratory to patient-'bench to bedside'

Large animal models have been widely used to facilitate the translation of mesenchymal stem cells (MSC) from the laboratory to patient. MSC, with their multi-potent capacity, have been proposed to have therapeutic benefits in a number of pathological conditions. Laboratory studies allow the investigation of cellular and molecular interactions, while small animal models allow initial 'proof of concept' experiments. Large animals (dogs, pigs, sheep, goats and horses) are more similar physiologically and structurally to man. These models have allowed clinically relevant assessments of safety, efficacy and dosing of different MSC sources prior to clinical trials. In this review, we recapitulate the use of large animal models to facilitate the use of MSC to treat myocardial infarction-an example of one large animal model being considered the 'gold standard' for research and osteoarthritis-an example of the complexities of using different large animal models in a multifactorial disease. These examples show how large animals can provide a research platform that can be used to evaluate the value of cell-based therapies and facilitate the process of 'bench to bedside'.

Interleukin-4 Gene Transfection and Spheroid Formation Potentiate Therapeutic Efficacy of Mesenchymal Stem Cells for Osteoarthritis

Osteoarthritis (OA) is a painful intractable disease that significantly affects patients' quality of life. However, current therapies, such as pain killers and joint replacement surgery, do not lead to cartilage protection. Mesenchymal stem cells (MSCs) have been proposed as an alternative strategy for OA therapy because MSCs can secrete chondroprotective and anti-inflammatory factors. However, interleukin-4 (IL-4), a potent anti-inflammatory cytokine, is barely produced by MSCs, and MSC therapy suffers from rapid MSC death following intra-articular implantation. MSCs in spheroids survive better than naïve MSCs in vitro and in vivo. IL-4-transfected MSCs in spheroids (IL-4 MSC spheroid) show increased chondroprotective and anti-inflammatory effects in an OA chondrocyte model in vitro. Following intra-articular implantation in OA rats, IL-4 MSC spheroids show better cartilage protection and pain relief than naïve MSCs. Thus, IL-4 MSC spheroid may potentiate the therapeutic efficacy of MSCs for OA.

Meniscus Repair and Regeneration: A Systematic Review from a Basic and Translational Science Perspective

Meniscus injuries are among the most common athletic injuries and result in functional impairment in the knee. Repair is crucial for pain relief and prevention of degenerative joint diseases like osteoarthritis. Current treatments, however, do not produce long-term improvements. Thus, recent research has been investigating new therapeutic options for regenerating injured meniscal tissue. This review comprehensively details the current methodologies being explored in the basic sciences to stimulate better meniscus injury repair. Furthermore, it describes how these preclinical strategies may improve current paradigms of how meniscal injuries are clinically treated through a unique and alternative perspective to traditional clinical methodology.

Effect of cell density on formation of three-dimensional cartilaginous constructs using fibrin & human osteoarthritic chondrocytes

Background & objectives:

Seeding density is one of the major parameters affecting the quality of tissue-engineered cartilage. The objective of this study was to evaluate different seeding densities of osteoarthritis chondrocytes (OACs) to obtain the highest quality cartilage.

Methods:

The OACs were expanded from passage 0 (P0) to P3, and cells in each passage were analyzed for gross morphology, growth rate, RNA expression and immunochemistry (IHC). The harvested OACs were assigned into two groups: low (1×10⁷ cells/ml) and high (3×10⁷ cells/ml) cell density. Three-dimensional (3D) constructs for each group were created using polymerised fibrin and cultured for 7, 14 and 21 days in vitro using chondrocyte growth medium. OAC constructs were analyzed with gross assessments and microscopic evaluation using standard histology, IHC and immunofluorescence staining, in addition to gene expression and biochemical analyses to evaluate tissue development.

Results:

Constructs with a high seeding density of 3×10⁷ cells/ml were associated with better quality cartilage-like tissue than those seeded with 1×10⁷ cells/ml based on overall tissue formation, cell association and extracellular matrix distribution. The chondrogenic properties of the constructs were further confirmed by the expression of genes encoding aggrecan core protein and collagen type II.

Interpretation & conclusions:

Our results confirmed that cell density was a significant factor affecting cell behaviour and aggregate production, and this was important for establishing good quality cartilage.

Meniscectomy-induced osteoarthritis in the sheep model for the investigation of therapeutic strategies: a systematic review

PURPOSE

One of the major risk factors for OA is meniscectomy (Mx) that causes a rapid and progressive OA. Mx has been employed in various animal models, especially in large ones, to study preclinical safety and strategy effectiveness to counteract OA. The aim of the present study is to review in vivo studies, performed in sheep and published in the last ten years.

METHODS

The search strategy was performed in three websites: www.scopus.com, www.pubmed.com, and www.webofknowledge.com, using "Meniscectomy and osteoarthritis in sheep" keywords.

RESULTS

The 25 included studies performed unilateral total medial Mx (MMx), unilateral partial MMx, bilateral MMx, unilateral total lateral Mx (LMx), unilateral partial LMx, and bilateral LMx and MMx combined with anterior cruciate ligament transaction. The most frequently performed is the unilateral total MMx that increases changes in cartilage and subchondral bone more than the other techniques. Gross evaluations, histology, radiography, and biochemical tests are used to assess the degree of OA. The most widely tested treatments are related to scaffolds with or without mesenchymal stem cells.

CONCLUSION

OA therapeutic strategies require the use of large animal models due to similarities with human joint anatomy. A protocol for future in vivo studies on post-traumatic OA is clarified.

Autologous stem cell-derived chondrocyte implantation with bio-targeted microspheres for the treatment of osteochondral defects

BACKGROUND

Chondral injury is a common problem around the world. Currently, there are several treatment strategies for these types of injuries. The possible complications and problems associated with conventional techniques lead us to investigate a minimally invasive and biotechnological alternative treatment. Combining tissue-engineering and microencapsulation technologies provide new direction for the development of biotechnological solutions. The aim of this study is to develop a minimal invasive tissue-engineering approach, using bio-targeted microspheres including autologous cells, for the treatment of the cartilage lesions.

METHOD

In this study, a total of 28 sheeps of Akkaraman breed were randomly assigned to one of the following groups: control (group 1), microfracture (group 2), scaffold (group 3), and microsphere (group 4). Microspheres and scaffold group animals underwent adipose tissue collection prior to the treatment surgery. Mesenchymal cells collected from adipose tissue were differentiated into chondrocytes and encapsulated with scaffolds and microspheres. Osteochondral damage was conducted in the right knee joint of the sheep to create an animal model and all animals treated according to study groups.

RESULTS

Both macroscopic and radiologic examination showed that groups 3 and 4 have resulted better compared to the control and microfracture groups. Moreover, histologic assessments indicate hyaline-like cartilage formations in groups 3 and 4.

CONCLUSION

In conclusion, we believe that the bio-targeted microspheres can be a more effective, easier, and safer approach for cartilage tissue engineering compared to previous alternatives.

Substantial Overview on Mesenchymal Stem Cell Biological and Physical Properties as an Opportunity in Translational Medicine

Mesenchymal stem cells (MSC) have piqued worldwide interest for their extensive potential to treat a large array of clinical indications, their unique and controversial immunogenic and immune modulatory properties allowing ample discussions and debates for their possible applications. Emerging data demonstrating that the interaction of biomaterials and physical cues with MSC can guide their differentiation into specific cell lineages also provide new interesting insights for further MSC manipulation in different clinical applications. Moreover, recent discoveries of some regulatory molecules and signaling pathways in MSC niche that may regulate cell fate to distinct lineage herald breakthroughs in regenerative medicine. Although the advancement and success in the MSC field had led to an enormous increase in the amount of ongoing clinical trials, we still lack defined clinical therapeutic protocols. This review will explore the exciting opportunities offered by human and animal MSC, describing relevant biological properties of these cells in the light of the novel emerging evidence mentioned above while addressing the limitations and challenges MSC are still facing.

Mesenchymal stem cell related therapies for cartilage lesions and osteoarthritis

Osteoarthritis (OA) is a common degenerative joint disease characterized by cartilage degradation, synovitis, subchondral bone sclerosis and osteophyte formation. Current therapeutic approaches for OA are not curative and only temporarily alleviate symptoms. In recent years, pre-clinical experiments and clinical trials have demonstrated that mesenchymal stem cell (MSC) related therapy is a promising option for the treatment of cartilage lesions and OA. MSCs isolated from bone marrow (BMSCs) have been widely used in animal models and clinic practice to demonstrate their chondrogenic potential, however the incidence of BMSC donors is low. Adipose derived mesenchymal stem cells (AMSCs) are a more easily accessible source of stem cells for OA treatment. MSC related therapies for cartilage lesions and OA include tissue engineering of MSC transplantation, scaffold-free injection of stem cells and cell-free injection of exosomes into the injured joints. Although a great deal of effort is required at the basic and clinical research fronts, the promise is that improved cell-based therapies will ultimately lead to the repair of damaged or diseased joints, and MSC exosome therapy for OA could be a safer, cheaper and a more effective treatment modality. MSC related therapy is predicted to become a regular and routine regenerative medicine for OA treatment in future clinical practice.

Regenerative Capacity of Adipose Derived Stem Cells (ADSCs), Comparison with Mesenchymal Stem Cells (MSCs)

Adipose tissue is now on the top one of stem cell sources regarding its accessibility, abundance, and less painful collection procedure when compared to other sources. The adipose derived stem cells (ADSCs) that it contains can be maintained and expanded in culture for long periods of time without losing their differentiation capacity, leading to large cell quantities being increasingly used in cell therapy purposes. Many reports showed that ADSCs-based cell therapy products demonstrated optimal efficacy and efficiency in some clinical indications for both autologous and allogeneic purposes, hence becoming considered as potential tools for replacing, repairing, and regenerating dead or damaged cells. In this review, we analyzed the therapeutic advancement of ADSCs in comparison to bone marrow (BM) and umbilical cord (UC)-mesenchymal stem cells (MSCs) and designed the specific requirements to their best clinical practices and safety. Our analysis was focused on the ADSCs, rather than the whole stromal vascular fraction (SVF) cell populations, to facilitate characterization that is related to their source of origins. Clinical outcomes improvement suggested that these cells hold great promise in stem cell-based therapies in neurodegenerative, cardiovascular, and auto-immunes diseases.

Regenerative Capacity of Adipose Derived Stem Cells (ADSCs), Comparison with Mesenchymal Stem Cells (MSCs)

Adipose tissue is now on the top one of stem cell sources regarding its accessibility, abundance, and less painful collection procedure when compared to other sources. The adipose derived stem cells (ADSCs) that it contains can be maintained and expanded in culture for long periods of time without losing their differentiation capacity, leading to large cell quantities being increasingly used in cell therapy purposes. Many reports showed that ADSCs-based cell therapy products demonstrated optimal efficacy and efficiency in some clinical indications for both autologous and allogeneic purposes, hence becoming considered as potential tools for replacing, repairing, and regenerating dead or damaged cells. In this review, we analyzed the therapeutic advancement of ADSCs in comparison to bone marrow (BM) and umbilical cord (UC)-mesenchymal stem cells (MSCs) and designed the specific requirements to their best clinical practices and safety. Our analysis was focused on the ADSCs, rather than the whole stromal vascular fraction (SVF) cell populations, to facilitate characterization that is related to their source of origins. Clinical outcomes improvement suggested that these cells hold great promise in stem cell-based therapies in neurodegenerative, cardiovascular, and auto-immunes diseases.

Anterior Cruciate Ligament Reconstruction in a Rabbit Model Using a Decellularized Allogenic Semitendinous Tendon Combined with Autologous Bone Marrow-Derived Mesenchymal Stem Cells

As a regular adoptable material for anterior cruciate ligament (ACL) reconstruction, free tendon allograft exhibits unsatisfactory outcomes, such as retarded ligamentization and tendon–bone integration. The application of bone marrow‐derived mesenchymal stem cells (BMSCs), as well as a decellularized free tendon allograft developed by our group, was proven to be effective in improving ACL reconstruction results. This study aimed to investigate the efficacy and feasibility of decellularized allogenic semitendinous tendon (ST) combined with autologous BMSCs used as a substitute to free tendon allograft in a rabbit model. This study finally shows that the decellularized allogenic ST combined with autologous BMSCs could significantly improve ACL reconstruction results compared with allograft. stem cells translational medicine2019;8:971&982

Articular cartilage regeneration and tissue engineering models: a systematic review

INTRODUCTION

Cartilage regeneration and restoration is a major topic in orthopedic research as cartilaginous degeneration and damage is associated with osteoarthritis and joint destruction. This systematic review aims to summarize current research strategies in cartilage regeneration research.

MATERIALS AND METHODS

A Pubmed search for models investigating single-site cartilage defects as well as chondrogenesis was conducted and articles were evaluated for content by title and abstract. Finally, only manuscripts were included, which report new models or approaches of cartilage regeneration.

RESULTS

The search resulted in 2217 studies, 200 of which were eligible for inclusion in this review. The identified manuscripts consisted of a large spectrum of research approaches spanning from cell culture to tissue engineering and transplantation as well as sophisticated computational modeling.

CONCLUSIONS

In the past three decades, knowledge about articular cartilage and its defects has multiplied in clinical and experimental settings and the respective body of research literature has grown significantly. However, current strategies for articular cartilage repair have not yet succeeded to replicate the structure and function of innate articular cartilage, which makes it even more important to understand the current strategies and their impact. Therefore, the purpose of this review was to globally summarize experimental strategies investigating cartilage regeneration in vitro as well as in vivo. This will allow for better referencing when designing new models or strategies and potentially improve research translation from bench to bedside.

Bone Marrow-Derived and Adipose-Derived Mesenchymal Stem Cell Therapy in Primary Knee Osteoarthritis: A Narrative Review

Regenerative medicine in the context of musculoskeletal injury is a broad term that offers potential therapeutic solutions to restore or repair damaged tissue. The current focus in recent literature and clinical practice has been on cell based therapy. In particular, much attention has been centered on autologous bone marrow concentrate and adipose-derived mesenchymal stem cells (MSCs) for cartilage and tendon disorders. This article provides an overview of MSC-derived therapy and offers a comprehensive review of adipose- and bone marrow-derived MSC therapy in primary knee osteoarthritis. LEVEL OF EVIDENCE: IV.