Autologous bone marrow stromal cell transplantation for repair of full-thickness articular cartilage defects in human patellae: two case reports

Comparative assessment of chondral defect repair using human bone marrow- and adipose tissue-derived mesenchymal stem cells, adult and foetal articular cartilage-derived chondrocytes, and chondroprogenitors: an ex-vivo model

PURPOSE

Cartilage repair necessitates adjunct therapies such as cell-based approaches, which commonly use MSCs and chondrocytes but is limited by the formation of fibro-hyaline cartilage. Articular cartilage-derived chondroprogenitors(CPs) offer promise in overcoming this, as they exhibit higher chondrogenic and lower hypertrophic phenotypes. The study aimed to compare the efficacy of various cell types derived from adult and foetal cartilage suspended in platelet-rich plasma(PRP) in repairing chondral defects in an Ex-vivo Osteochondral Unit(OCU) model.

METHODS

In-vitro characterization of the cells included growth kinetics, FACS, qRT-PCR, and multilineage differentiation potential using histology and GAG analysis. Ex-vivo human OCUs with chondral defects containing the different cells in PRP were cultured and subjected to analysis for matrix and collagen staining.

RESULTS

The ex-vivo OCU analysis, in terms of defect repair, showed that adult chondrocytes, sorted-CPs, and foetal MCPs displayed better host integration and filling. The In-vitro analysis of adult chondrocytes displayed greater chondrogenic genes ACAN and COL2A1 expression, with sorted-CPs also showing higher levels of ACAN. In terms of accumulation of extracellular matrix uptake evident by Safranin O staining and collagen type II fibrillar uptake, the AD-MSCs, BM-MSCs, and sorted CPs outperformed the other groups. BM-MSCs also showed corroborative higher CD146 levels, however, the gene analysis of the AD-MSCs showed a high hypertrophic tendency in terms of its COL1A1 and RUNX2 expression.

CONCLUSION

Sorted chondroprogenitors outperformed both in terms of filling and hyaline-like repair, with AD-MSC and BM-MSC groups also achieving functional cartilage of a hyaline nature, warranting further evaluation using in-vivo and clinical studies.

The Synovial Sealant Variant for Minced Cartilage Repair: A Technical Note and Retrospective Study

Purpose

Cartilage defects are a common pathology in active people and affect quality of life. A common treatment option is treatment with minced cartilage (MC). As conservative therapy has a limited effect, surgical treatments vary in terms of procedure and results. A modified technique for autologous cartilage repair is presented here.

Method

MC was modified by adding a synovial sealant. This improves the stability of the graft, allowing the cartilage to proliferate. The synovial tissue has the potential to stimulate the implanted cartilage, which promotes healing and regeneration. The clinical and functional results of the modified technique were examined in a retrospective case series.

Results

The technique has proven to be reproducible for retropatellar cartilage defects and is both efficient and cost effective. MC with synovial sealing was performed in ten patients with retropatellar cartilage damage. In the conducted cases serious, 10 patients were available for follow-up after 18 ± 3 months. Patients showed good clinical results in terms of pain (VAS = 1.9, KOOS Pain = 89.7), symptoms (KOOS Symptoms = 83.6), and daily activity (KOOS Activity = 96.6).

Conclusion

The procedure combines the advantages of autologous cartilage repair with a one-stage surgical approach. It utilizes the regenerative potential of synovial tissue while providing improved mechanical stability. This technique offers a cost-effective, autologous solution for full-thickness cartilage defects, and shows promising clinical results in the medium term.

3D Bioprinting of Hyaline Cartilage Using Nasal Chondrocytes

Due to the limited self-repair capacity of the hyaline cartilage, the repair of cartilage remains an unsolved clinical problem. Tissue engineering strategy with 3D bioprinting technique has emerged a new insight by providing patient's personalized cartilage grafts using autologous cells for hyaline cartilage repair and regeneration. In this review, we first summarized the intrinsic property of hyaline cartilage in both maxillofacial and orthopedic regions to establish the requirement for 3D bioprinting cartilage tissue. We then reviewed the literature and provided opinion pieces on the selection of bioprinters, bioink materials, and cell sources. This review aims to identify the current challenges for hyaline cartilage bioprinting and the directions for future clinical development in bioprinted hyaline cartilage.

Review of Caplan (1991) on cell-based therapeutic technology using Mesenchymal Stem Cells

This classic discusses the original 1991 publication 'Mesenchymal Stem Cells (MSCs)' by Dr. Caplan on the emergence of a new therapeutic technology of self-cell repair using MSCs. After the original classic publication, a large number of methods to regenerate injured tissue have been reported. Currently, MSCs are used clinically to repair articular cartilage defects, liver cirrhosis, cerebral infarction, spinal cord injury, graft-versus-host disease and others. As a result, MSCs are considered one of the most important cell sources for regenerative medicine. An MSC has been demonstrated to be a multipotent stem cell in cell culture and was thought to contribute to the regeneration of injured tissue at transplant sites, but recently, the concept of MSCs has changed such that they are now referred to as "medicinal signaling cells," owing to their often indirect effects on tissue repair and regeneration. Regardless of the name, either mesenchymal stem cells or medicinal signaling cells, MSCs will be used to regenerate injured tissue more widely in the near future.

Exosomes derived from MSC as drug system in osteoarthritis therapy

Osteoarthritis (OA) is the most common degenerative disease of the joint with irreversible cartilage damage as the main pathological feature. With the development of regenerative medicine, mesenchymal stem cells (MSCs) have been found to have strong therapeutic potential. However, intraarticular MSCs injection therapy is limited by economic costs and ethics. Exosomes derived from MSC (MSC-Exos), as the important intercellular communication mode of MSCs, contain nucleic acid, proteins, lipids, microRNAs, and other biologically active substances. With excellent editability and specificity, MSC-Exos function as a targeted delivery system for OA treatment, modulating immunity, inhibiting apoptosis, and promoting regeneration. This article reviews the mechanism of action of MSC-Exos in the treatment of osteoarthritis, the current research status of the preparation of MSC-Exos and its application of drug delivery in OA therapy.

Advances in Stem Cell-Based Therapies in the Treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic, degenerative joint disease presenting a significant global health threat. While current therapeutic approaches primarily target symptom relief, their efficacy in repairing joint damage remains limited. Recent research has highlighted mesenchymal stem cells (MSCs) as potential contributors to cartilage repair, anti-inflammatory modulation, and immune regulation in OA patients. Notably, MSCs from different sources and their derivatives exhibit variations in their effectiveness in treating OA. Moreover, pretreatment and gene editing techniques of MSCs can enhance their therapeutic outcomes in OA. Additionally, the combination of novel biomaterials with MSCs has shown promise in facilitating the repair of damaged cartilage. This review summarizes recent studies on the role of MSCs in the treatment of OA, delving into their advantages and exploring potential directions for development, with the aim of providing fresh insights for future research in this critical field.

Investigating the Interplay Between Matrix Compliance and Passaging History on Chondrogenic Differentiation of Mesenchymal Stem Cells Encapsulated Within Alginate-Gelatin Hybrid Hydrogels

Mesenchymal stem cells (MSCs) are used widely in tissue engineering and regenerative medicine because of their ease of isolation and their pluripotency. The low survival and retention rate of MSCs at the target site upon implantation can be addressed via encapsulation within hydrogels capable of directing their fate. In this study, the interplay between matrix mechanics and the passage number of MSCs on their chondrogenic differentiation was assessed. Human bone marrow-derived MSCs between passages 4 and 6 were encapsulated within alginate-gelatin hybrid gels. The stiffness of the gels was varied by varying alginate concentrations while maintaining the concentration of gelatin and consequently, the cell adhesion sites, constant. The study revealed that within 4.8 kPa gels, GAG deposition was higher by P4 MSCs compared to P6 MSCs. However, an opposite trend was observed with collagen type 2 deposition. Further, we observed enhanced chondrogenic differentiation upon encapsulation of MSCs within 6.7 kPa hydrogel irrespective of passaging history. However, the effect of matrix compliance was more prominent in the case of higher passaged MSCs suggesting that matrix stiffness can help rescue the reduced differentiation capability of these cells.

Bioactivity of human adult stem cells and functional relevance of stem cell-derived extracellular matrix in chondrogenesis

BACKGROUND

Autologous chondrocyte implantation (ACI) has been used to treat articular cartilage defects for over two decades. Adult stem cells have been proposed as a solution to inadequate donor cell numbers often encountered in ACI. Multipotent stem/progenitor cells isolated from adipose, bone marrow, and cartilage are the most promising cell therapy candidates. However, different essential growth factors are required to induce these tissue-specific stem cells to initiate chondrogenic differentiation and subsequent deposition of extracellular matrix (ECM) to form cartilage-like tissue. Upon transplantation into cartilage defects in vivo, the levels of growth factors in the host tissue are likely to be inadequate to support chondrogenesis of these cells in situ. The contribution of stem/progenitor cells to cartilage repair and the quality of ECM produced by the implanted cells required for cartilage repair remain largely unknown. Here, we evaluated the bioactivity and chondrogenic induction ability of the ECM produced by different adult stem cells.

METHODS

Adult stem/progenitor cells were isolated from human adipose (hADSCs), bone marrow (hBMSCs), and articular cartilage (hCDPCs) and cultured for 14 days in monolayer in mesenchymal stromal cell (MSC)-ECM induction medium to allow matrix deposition and cell sheet formation. The cell sheets were then decellularized, and the protein composition of the decellularized ECM (dECM) was analyzed by BCA assay, SDS-PAGE, and immunoblotting for fibronectin (FN), collagen types I (COL1) and III (COL3). The chondrogenic induction ability of the dECM was examined by seeding undifferentiated hBMSCs onto the respective freeze-dried solid dECM followed by culturing in serum-free medium for 7 days. The expression levels of chondrogenic genes SOX9, COL2, AGN, and CD44 were analyzed by q-PCR.

RESULTS

hADSCs, hBMSCs, and hCDPCs generated different ECM protein profiles and exhibited significantly different chondrogenic effects. hADSCs produced 20-60% more proteins than hBMSCs and hCDPCs and showed a fibrillar-like ECM pattern (FN^high, COL1^high). hCDPCs produced more COL3 and deposited less FN and COL1 than the other cell types. The dECM derived from hBMSCs and hCDPCs induced spontaneous chondrogenic gene expression in hBMSCs.

CONCLUSIONS

These findings provide new insights on application of adult stem cells and stem cell-derived ECM to enhance cartilage regeneration.

Advantages of mesenchymal stem cell over the other stem cells

A stem cell is a particular group of cells that has the extraordinary potential to convert within the body into particular cell types. They are used to regenerate tissues and cells in the body that have been damaged or destroyed by the disease. Stem cells come in three different varieties: adult stem cells, embryonic stem cells and induced pluripotent stem cells (iPSCs). Embryonic stem cells have a high chance of immune rejection and also have ethical dilemmas and iPSCs have genetic instability. Adult stem cells are difficult to analyze and extract for research since they are frequently insufficient in native tissues. However, mesenchymal stem cells (MSC) one of the categories of adult stem cells are stromal cells with a variety of potentials that can differentiate into a wide range of cell types. MSCs can be transplanted into a variety of people without worrying about rejection because they have demonstrated the ability to prevent an adverse reaction from the immune system. These transplants have powerful anti-inflammatory and immunosuppressive effects and greatly enhance the body's inherent healing capacity. While MSCs do not offer treatment for illnesses, the idea behind them is to enable the body to recover sufficiently for a protracted reduction in symptoms. In many cases, this is sufficient to significantly enhance the patient's well-being. Inspite of several advantages some potential long-term concerns connected to MSC therapy are maldifferentiation, immunosuppression and cancerous tumor growth. In this review, we will compare the mesenchymal stem cells with other stem cells with respect to the source of origin, their properties and therapeutic applications, and discuss the MSC's disadvantages.

Progress and emerging techniques for biomaterial-based derivation of mesenchymal stem cells (MSCs) from pluripotent stem cells (PSCs)

The use of mesenchymal stem cells (MSCs) for clinical purposes has skyrocketed in the past decade. Their multilineage differentiation potentials and immunomodulatory properties have facilitated the discovery of therapies for various illnesses. MSCs can be isolated from infant and adult tissue sources, which means they are easily available. However, this raises concerns because of the heterogeneity among the various MSC sources, which limits their effective use. Variabilities arise from donor- and tissue-specific differences, such as age, sex, and tissue source. Moreover, adult-sourced MSCs have limited proliferation potentials, which hinders their long-term therapeutic efficacy. These limitations of adult MSCs have prompted researchers to develop a new method for generating MSCs. Pluripotent stem cells (PSCs), such as embryonic stem cells and induced PSCs (iPSCs), can differentiate into various types of cells. Herein, a thorough review of the characteristics, functions, and clinical importance of MSCs is presented. The existing sources of MSCs, including adult- and infant-based sources, are compared. The most recent techniques for deriving MSCs from iPSCs, with a focus on biomaterial-assisted methods in both two- and three-dimensional culture systems, are listed and elaborated. Finally, several opportunities to develop improved methods for efficiently producing MSCs with the aim of advancing their various clinical applications are described.

Regeneration of Humeral Head Using a 3D Bioprinted Anisotropic Scaffold with Dual Modulation of Endochondral Ossification

Tissue engineering is theoretically thought to be a promising method for the reconstruction of biological joints, and thus, offers a potential treatment alternative for advanced osteoarthritis. However, to date, no significant progress is made in the regeneration of large biological joints. In the current study, a biomimetic scaffold for rabbit humeral head regeneration consisting of heterogeneous porous architecture, various bioinks, and different hard supporting materials in the cartilage and bone regions is designed and fabricated in one step using 3D bioprinting technology. Furthermore, orchestrated dynamic mechanical stimulus combined with different biochemical cues (parathyroid hormone [PTH] and chemical component hydroxyapatite [HA] in the outer and inner region, respectively) are used for dual regulation of endochondral ossification. Specifically, dynamic mechanical stimulus combined with growth factor PTH in the outer region inhibits endochondral ossification and results in cartilage regeneration, whereas dynamic mechanical stimulus combined with HA in the inner region promotes endochondral ossification and results in efficient subchondral bone regeneration. The strategy established in this study with the dual modulation of endochondral ossification for 3D bioprinted anisotropic scaffolds represents a versatile and scalable approach for repairing large joints.

Transcriptomic response of bioengineered human cartilage to parabolic flight microgravity is sex-dependent

Spaceflight and simulated spaceflight microgravity induced osteoarthritic-like alterations at the transcriptomic and proteomic levels in the articular and meniscal cartilages of rodents. But little is known about the effect of spaceflight or simulated spaceflight microgravity on the transcriptome of tissue-engineered cartilage developed from human cells. In this study, we investigate the effect of simulated spaceflight microgravity facilitated by parabolic flights on tissue-engineered cartilage developed from in vitro chondrogenesis of human bone marrow mesenchymal stem cells obtained from age-matched female and male donors. The successful induction of cartilage-like tissue was confirmed by the expression of well-demonstrated chondrogenic markers. Our bulk transcriptome data via RNA sequencing demonstrated that parabolic flight altered mostly fundamental biological processes, and the modulation of the transcriptome profile showed sex-dependent differences. The secretome profile analysis revealed that two genes (WNT7B and WNT9A) from the Wnt-signaling pathway, which is implicated in osteoarthritis development, were only up-regulated for female donors. The results of this study showed that the engineered cartilage tissues responded to microgravity in a sex-dependent manner, and the reported data offers a strong foundation to further explore the underlying mechanisms.

Extracellular vesicles in osteoarthritis of peripheral joint and temporomandibular joint

Osteoarthritis (OA) is a disabling disease with significant morbidity worldwide. OA attacks the large synovial joint, including the peripheral joints and temporomandibular joint (TMJ). As a representative of peripheral joint OA, knee OA shares similar symptoms with TMJ OA. However, these two joints also display differences based on their distinct development, anatomy, and physiology. Extracellular vesicles (EVs) are phospholipid bilayer nanoparticles, including exosomes, microvesicles, and apoptotic bodies. EVs contain proteins, lipids, DNA, micro-RNA, and mRNA that regulate tissue homeostasis and cell-to-cell communication, which play an essential role in the progression and treatment of OA. They are likely to partake in mechanical response, extracellular matrix degradation, and inflammatory regulation during OA. More evidence has shown that synovial fluid and synovium-derived EVs may serve as OA biomarkers. More importantly, mesenchymal stem cell-derived EV shows a therapeutic effect on OA. However, the different function of EVs in these two joints is largely unknown based on their distinct biological characteristic. Here, we reviewed the effects of EVs in OA progression and compared the difference between the knee joint and TMJ, and summarized their potential therapeutic role in the treatment of OA.

Potency Assay Considerations for Cartilage Repair, Osteoarthritis and Use of Extracellular Vesicles

Articular cartilage covers the ends of bones in synovial joints acting as a shock absorber that helps movement of bones. Damage of the articular cartilage needs treatment as it does not repair itself and the damage can progress to osteoarthritis. In osteoarthritis all the joint tissues are involved with characteristic progressive cartilage degradation and inflammation. Autologous chondrocyte implantation is a well-proven cell-based treatment for cartilage defects, but a main downside it that it requires two surgeries. Multipotent, aka mesenchymal stromal cell (MSC)-based cartilage repair has gained attention as it can be used as a one-step treatment. It is proposed that a combination of immunomodulatory and regenerative capacities make MSC attractive for the treatment of osteoarthritis. Furthermore, since part of the paracrine effects of MSCs are attributed to extracellular vesicles (EVs), small membrane enclosed particles secreted by cells, EVs are currently being widely investigated for their potential therapeutic effects. Although MSCs have entered clinical cartilage treatments and EVs are used in in vivo efficacy studies, not much attention has been given to determine their potency and to the development of potency assays. This chapter provides considerations and suggestions for the development of potency assays for the use of MSCs and MSC-EVs for the treatment of cartilage defects and osteoarthritis.

Chondrogenic differentiation of human bone marrow MSCs in osteochondral implants under kinematic mechanical load is dependent on the underlying osteo component

Chondrogenic models utilizing human mesenchymal stromal cells (hMSCs) are often simplistic, with a single cell type and the absence of mechanical stimulation. Considering the articulating joint as an organ it would be beneficial to include more complex stimulation. Within this study we applied clinically relevant kinematic load to biphasic constructs. In each case, the upper layer consisted of fibrin embedded hMSCs retained within an elastomeric polyurethane (PU) scaffold. These were randomly assigned to five base scaffolds, a cell-free fibrin PU base, viable bone, decellularized bone, 3D printed calcium phosphate or clinically used cement. This allowed the study of cross talk between viable bone and chondrogenically differentiating MSCs, while controlling for the change in stiffness of the base material. Data obtained showed that the bulk stiffness of the construct was not the defining factor in the response obtained, with viable and decellularized bone producing similar results to the softer PU base. However, the stiff synthetic materials led to reduced chondrogenesis and increased calcification in the upper MSC seeded layer. This demonstrates that the underlying base material must be considered when driving chondrogenesis of human cells using a clinically relevant loading protocol. It also indicates that the material used for bony reconstruction of osteochondral defects may influence subsequent chondrogenic potential.

Chondroprotective Effects of Periodontal Ligament Derived Stem Cells Conditioned Medium on Articular Cartilage After Impact Injury

Paracrine factors secreted in the conditioned media of periodontal ligament derived stem cells (PDLSCs) have been shown to downregulate inflammatory effects of IL-1β on chondrocytes wherein milk fat globule-epidermal growth factor 8 (MFG-E8) is one of the PDLSCs highly secretory proteins. Therefore, the objective of this study was to investigate the ability of PDLSC conditioned media (CM) and MFG-E8 to reduce the inflammatory effects of impact injury on porcine talar articular cartilage (AC) and IL-1β on chondrocytes, respectively. Stem cells were isolated from human periodontal ligaments. the MFG-E8 content in CM collected at 5% and 20% oxygen was measured by ELISA assay and compared across subcultures and donors. AC samples were divided into three groups: control, impact, and impact+CM. Chondrocytes were isolated from pig knees and were divided into three groups: control, IL-1β, and IL-1β+MFG-E8. Gene expression data was analyzed by RT-PCR. It was found that impact load and IL-1β treatment upregulated IL-1β, TNF-α, ADAMTS-4, and ADAMTS-5 gene expression in AC and chondrocytes, respectively. PDLSCs-CM prevented the upregulation of all four genes due to impact whereas MFG-E8 prevented upregulation of IL-1β, ADAMTS-4, and ADAMTS-5 in chondrocytes, but it did not prevent TNF-α upregulation. There were no significant differences in MFG-E8 content in CM among oxygen levels, passage numbers, or donors. The findings suggested that MFG-E8 is an effective anti-inflammatory agent contributing to the chondroprotective effects of PDLSCs-CM on acutely injured articular cartilage. Thus, introducing PDLSCs-CM to sites of acute traumatic AC injury could prevent the development of post-traumatic osteoarthritis.

Stepwise Proliferation and Chondrogenic Differentiation of Mesenchymal Stem Cells in Collagen Sponges under Different Microenvironments

Biomimetic microenvironments are important for controlling stem cell functions. In this study, different microenvironmental conditions were investigated for the stepwise control of proliferation and chondrogenic differentiation of human bone-marrow-derived mesenchymal stem cells (hMSCs). The hMSCs were first cultured in collagen porous sponges and then embedded with or without collagen hydrogels for continual culture under different culture conditions. The different influences of collagen sponges, collagen hydrogels, and induction factors were investigated. The collagen sponges were beneficial for cell proliferation. The collagen sponges also promoted chondrogenic differentiation during culture in chondrogenic medium, which was superior to the effect of collagen sponges embedded with hydrogels without loading of induction factors. However, collagen sponges embedded with collagen hydrogels and loaded with induction factors had the same level of promotive effect on chondrogenic differentiation as collagen sponges during in vitro culture in chondrogenic medium and showed the highest promotive effect during in vivo subcutaneous implantation. The combination of collagen sponges with collagen hydrogels and induction factors could provide a platform for cell proliferation at an early stage and subsequent chondrogenic differentiation at a late stage. The results provide useful information for the chondrogenic differentiation of stem cells and cartilage tissue engineering.

The 50 most-cited clinical articles in cartilage surgery research: a bibliometric analysis

PURPOSE

Articular cartilage lesions remain a challenge for orthopedic surgeons. The identification of the most important articles can help identifying the most influential techniques of the past, the current prevalent focus, and emerging strategies. The aim of this study was to identify milestones and trends in cartilage research.

METHODS

This study is a bibliometric analysis based on published articles. All citation count data included in the "Scopus database" were used to identify eligible studies up to December 2020. The 50 most-cited articles on cartilage surgery were ranked based on the citation count and analyzed regarding citation density and quality (Coleman score and RoB 2.0 tool). A further search was performed to identify the most promising clinical studies among the latest publications on cartilage surgery.

RESULTS

Different kinds of cartilage treatments were investigated in the 50 most-cited clinical articles. Regenerative techniques with chondrocytes were the most reported with a total of 23 articles, followed by microfracture technique in 17 articles and mosaicplasty or osteochondral autograft transplantation (OAT) in 11. Forty-five articles focused on the knee. A higher citation density was found in the most recent articles (p = 0.004). The study of the most promising landmarks of the most recent articles showed new cell-free or tissue engineering-based procedures and an overall increasing quality of the published studies.

CONCLUSION

This bibliometric analysis documented an increasing interest in cartilage surgery, with efforts toward high-quality studies. Over the years, the focus switched from reconstructive toward regenerative techniques, with emerging options including cell-free and tissue-engineering strategies to restore the cartilage surface.

LEVEL OF EVIDENCE

IV.

Injectable cultured bone marrow derived mesenchymal cells vs chondrocytes in the treatment of chondral defects of the knee - RCT with 6 years follow-up

Articular cartilage has unique biological and biomechanical characteristics. Damage to this tissue fails to heal spontaneously, leading to progressive arthritis. Cartilage repair techniques have been looked forward to in the treatment of significant cartilage injuries. Cell-based regenerative techniques like the two-staged cultured chondrocytes and single-stage mesenchymal cell transplantation have been tried with varying results and limitations. We study the outcomes of cultured bone marrow derived MSCs in the treatment of articular cartilage defects of the knee in comparison to autologous cultured chondrocyte implantation (ACI). Both cultured MSC and ACI treatment methods resulted in significant improvements in patient reported outcome measures (PROMs). There was no difference in the PROMs, MOCART scores, T2∗ mapping and dGEMRIC values between the groups. Use of cultured MSCs leads to good clinical outcomes similar to ACI and represents a promising treatment to restore the articular cartilage in the knee.

Three-dimensional Culture and Chondrogenic Differentiation of Mesenchymal Stem Cells in Interconnected Collagen Scaffolds

Interconnected scaffolds are useful for promoting the chondrogenic differentiation of stem cells. Collagen scaffolds with interconnected pore structures were fabricated with poly(lactic acid-co-glycolic acid) (PLGA) sponge templates. The PLGA-templated collagen scaffolds were used to culture human bone marrow-derived mesenchymal stem cells (hMSCs) to investigate their promotive effect on the chondrogenic differentiation of hMSCs. The cells adhered to the scaffolds with a homogeneous distribution and proliferated with culture time. The expression of chondrogenesis-related genes was upregulated, and abundant cartilaginous matrices were detected. After subcutaneous implantation, the PLGA-templated collagen scaffolds further enhanced the production of cartilaginous matrices and the mechanical properties of the implants. The good interconnectivity of the PLGA-templated collagen scaffolds promoted chondrogenic differentiation. In particular, the collagen scaffolds prepared with large pore-bearing PLGA sponge templates showed the highest promotive effect.

Treatment of osteoarthritis with autologous, micro-fragmented adipose tissue: a study protocol for a randomized controlled trial

BACKGROUND

Osteoarthritis is a destructive joint disease that leads to degeneration of cartilage and other morphological changes in the joint. No medical treatment currently exists that can reverse these morphological changes. Intra-articular injection with autologous, micro-fragmented adipose tissue has been suggested to relieve symptoms.

METHODS/DESIGN

The study is a blinded randomized controlled trial with patients allocated in a 1:1 ratio to 2 parallel groups. Patients suffering from pain and functional impairment due to osteoarthritis Kellgren-Lawrence grades 2-3 in the tibiofemoral joint are eligible for inclusion. The intervention group is treated with an intra-articular injection with autologous, micro-fragmented adipose tissue prepared using the Lipogems® system. The control group receives an intra-articular injection with isotonic saline. In total, 120 patients are to be included. The primary outcome is The Knee injury and Osteoarthritis Outcome Score (KOOS4) evaluated at 6 months. Secondary outcomes are KOOS at 3, 12 and 24 months; the Tegner activity score; treatment failure; and work status of the patient. The analysis will be conducted both as intention-to-treat and per-protocol analysis.

DISCUSSION

This trial is the first to investigate the efficacy of autologous, micro-fragmented adipose tissue in a randomized controlled trial. The study uses the patient-reported outcome measure Knee Injury and Osteoarthritis Outcome Score (KOOS4) after 6 months as the primary outcome, as it is believed to be a valid measure to assess the patient's opinion about their knee and associated problems when suffering from osteoarthritis.

Cell Sources for Cartilage Repair-Biological and Clinical Perspective

Cell-based therapy represents a promising treatment strategy for cartilage defects. Alone or in combination with scaffolds/biological signals, these strategies open many new avenues for cartilage tissue engineering. However, the choice of the optimal cell source is not that straightforward. Currently, various types of differentiated cells (articular and nasal chondrocytes) and stem cells (mesenchymal stem cells, induced pluripotent stem cells) are being researched to objectively assess their merits and disadvantages with respect to the ability to repair damaged articular cartilage. In this paper, we focus on the different cell types used in cartilage treatment, first from a biological scientist’s perspective and then from a clinician’s standpoint. We compare and analyze the advantages and disadvantages of these cell types and offer a potential outlook for future research and clinical application.

Extracellular Vesicles from Mesenchymal Stem Cells as Potential Treatments for Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disorder of the joint and its prevalence and severity is increasing owing to ageing of the population. Osteoarthritis is characterized by the degradation of articular cartilage and remodeling of the underlying bone. There is little understanding of the cellular and molecular processes involved in pathophysiology of OA. Currently the treatment for OA is limited to painkillers and anti-inflammatory drugs, which only treat the symptoms. Some patients may also undergo surgical procedures to replace the damaged joints. Extracellular vesicles (EV) play an important role in intercellular communications and their concentration is elevated in the joints of OA patients, although their mechanism is unclear. Extracellular vesicles are naturally released by cells and they carry their origin cell information to be delivered to target cells. On the other hand, mesenchymal stem cells (MSCs) are highly proliferative and have a great potential in cartilage regeneration. In this review, we provide an overview of the current OA treatments and their limitations. We also discuss the role of EV in OA pathophysiology. Finally, we highlight the therapeutic potential of MSC-derived EV in OA and their challenges.

Comparative evaluation of isogenic mesodermal and ectomesodermal chondrocytes from human iPSCs for cartilage regeneration

Generating phenotypic chondrocytes from pluripotent stem cells is of great interest in the field of cartilage regeneration. In this study, we differentiated human induced pluripotent stem cells into the mesodermal and ectomesodermal lineages to prepare isogenic mesodermal cell-derived chondrocytes (MC-Chs) and neural crest cell-derived chondrocytes (NCC-Chs), respectively, for comparative evaluation. Our results showed that both MC-Chs and NCC-Chs expressed hyaline cartilage-associated markers and were capable of generating hyaline cartilage-like tissue ectopically and at joint defects. Moreover, NCC-Chs revealed closer morphological and transcriptional similarities to native articular chondrocytes than MC-Chs. NCC-Ch implants induced by our growth factor mixture demonstrated increased matrix production and stiffness compared to MC-Ch implants. Our findings address how chondrocytes derived from pluripotent stem cells through mesodermal and ectomesodermal differentiation are different in activities and functions, providing the crucial information that helps make appropriate cell choices for effective regeneration of articular cartilage.

Anti-Inflammatory Effects of Conditioned Medium of Periodontal Ligament-Derived Stem Cells on Chondrocytes, Synoviocytes, and Meniscus Cells

Osteoarthritis (OA) is the most common type of arthritis, afflicting millions of people in the world. Elevation of inflammatory mediators and enzymatic matrix destruction is often associated with OA. Therefore, the objective of this study was to investigate the effects of conditioned medium from periodontal ligament-derived stem cells (PDLSCs) on inflammatory and catabolic gene expressions of chondrocytes, synoviocytes, and meniscus cells under in vitro inflammatory condition. Stem cells were isolated from human periodontal ligaments. Conditioned medium was collected and concentrated 20 × . Chondrocytes, synoviocytes, and meniscus cells were isolated from pig knees and divided into four experimental groups: serum-free media, serum-free media+interleukin-1β (IL-1β) (10 ng/mL), conditioned media (CM), and CM+IL-1β. Protein content and extracellular vesicle (EV) miRNAs of CM were analyzed by liquid chromatography-tandem mass spectrometry and RNA sequencing, respectively. It was found that the IL-1β treatment upregulated the expression of IL-1β, tumor necrosis factor-α (TNF-α), MMP-13, and ADAMTS-4 genes in the three cell types, whereas PDLSC-conditioned medium prevented the upregulation of gene expression by IL-1β in all three cell types. This study also found that there was consistency in anti-inflammatory effects of PDLSC CM across donors and cell subcultures, while PDLSCs released several anti-inflammatory factors and EV miRNAs at high levels. OA has been suggested as an inflammatory disease in which all intrasynovial tissues are involved. PDLSC-conditioned medium is a cocktail of trophic factors and EV miRNAs that could mediate different inflammatory processes in various tissues in the joint. Introducing PDLSC-conditioned medium to osteoarthritic joints could be a potential treatment to prevent OA progression by inhibiting inflammation.

In Vivo Cartilage Regeneration with Cell-Seeded Natural Biomaterial Scaffold Implants: 15-Year Study

Articular cartilage can be easily damaged from human's daily activities, leading to inflammation and to osteoarthritis, a situation that can diminish the patients' quality of life. For larger cartilage defects, scaffolds are employed to provide cells the appropriate three-dimensional environment to proliferate and differentiate into healthy cartilage tissue. Natural biomaterials used as scaffolds, attract researchers' interest because of their relative nontoxic nature, their abundance as natural products, their easy combination with other materials, and the relative easiness to establish Marketing Authorization. The last 15 years were chosen to review, document, and elucidate the developments on cell-seeded natural biomaterials for articular cartilage treatment in vivo. The parameters of the experimental designs and their results were all documented and presented. Considerations about the newly formed cartilage and the treatment of cartilage defects were discussed, along with difficulties arising when applying natural materials, research limitations, and tissue engineering approaches for hyaline cartilage regeneration.

Recent Developments in Clinical Applications of Mesenchymal Stem Cells in the Treatment of Rheumatoid Arthritis and Osteoarthritis

Mesenchymal stem cell (MSC) therapies have been used as cell-based treatments for decades, owing to their anti-inflammatory, immunomodulatory, and regenerative properties. With high expectations, many ongoing clinical trials are investigating the safety and efficacy of MSC therapies to treat arthritic diseases. Studies on osteoarthritis (OA) have shown positive clinical outcomes, with improved joint function, pain level, and quality of life. In addition, few clinical MSC trials conducted on rheumatoid arthritis (RA) patients have also displayed some optimistic outlook. The largely positive outcomes in clinical trials without severe side effects establish MSCs as promising tools for arthritis treatment. However, further research is required to investigate its applicability in clinical settings. This review discusses the most recent advances in clinical studies on MSC therapies for OA and RA.

Perlecan in the Natural and Cell Therapy Repair of Human Adult Articular Cartilage: Can Modifications in This Proteoglycan Be a Novel Therapeutic Approach?

Articular cartilage is considered to have limited regenerative capacity, which has led to the search for therapies to limit or halt the progression of its destruction. Perlecan, a multifunctional heparan sulphate (HS) proteoglycan, promotes embryonic cartilage development and stabilises the mature tissue. We investigated the immunolocalisation of perlecan and collagen between donor-matched biopsies of human articular cartilage defects (n = 10 × 2) that were repaired either naturally or using autologous cell therapy, and with age-matched normal cartilage. We explored how the removal of HS from perlecan affects human chondrocytes in vitro. Immunohistochemistry showed both a pericellular and diffuse matrix staining pattern for perlecan in both natural and cell therapy repaired cartilage, which related to whether the morphology of the newly formed tissue was hyaline cartilage or fibrocartilage. Immunostaining for perlecan was significantly greater in both these repair tissues compared to normal age-matched controls. The immunolocalisation of collagens type III and VI was also dependent on tissue morphology. Heparanase treatment of chondrocytes in vitro resulted in significantly increased proliferation, while the expression of key chondrogenic surface and genetic markers was unaffected. Perlecan was more prominent in chondrocyte clusters than in individual cells after heparanase treatment. Heparanase treatment could be a means of increasing chondrocyte responsiveness to cartilage injury and perhaps to improve repair of defects.

Promoting Effect of Basic Fibroblast Growth Factor in Synovial Mesenchymal Stem Cell-Based Cartilage Regeneration

Synovial mesenchymal stem cell (SMSC) is the promising cell source of cartilage regeneration but has several issues to overcome such as limited cell proliferation and heterogeneity of cartilage regeneration ability. Previous reports demonstrated that basic fibroblast growth factor (bFGF) can promote proliferation and cartilage differentiation potential of MSCs in vitro, although no reports show its beneficial effect in vivo. The purpose of this study is to investigate the promoting effect of bFGF on cartilage regeneration using human SMSC in vivo. SMSCs were cultured with or without bFGF in a growth medium, and 2 × 10⁵ cells were aggregated to form a synovial pellet. Synovial pellets were implanted into osteochondral defects induced in the femoral trochlea of severe combined immunodeficient mice, and histological evaluation was performed after eight weeks. The presence of implanted SMSCs was confirmed by the observation of human vimentin immunostaining-positive cells. Interestingly, broad lacunae structures and cartilage substrate stained by Safranin-O were observed only in the bFGF (+) group. The bFGF (+) group had significantly higher O’Driscoll scores in the cartilage repair than the bFGF (−) group. The addition of bFGF to SMSC growth culture may be a useful treatment option to promote cartilage regeneration in vivo.

Isolation and Characterization of Human Synovial Fluid-Derived Mesenchymal Stromal Cells from Popliteal Cyst

Mesenchymal stem cells (MSCs) are multipotent progenitor cells in adult tissues. The aim of this study is to isolate and identify synovial fluid-derived mesenchymal stromal cells (SF-MSCs) from the popliteal cyst fluid of pediatric patients. SF-MSCs were collected from the popliteal cyst fluid of pediatric patients during cystectomy surgery. After cyst fluid extraction and adherent culturing, in vitro morphology, growth curve, and cell cycle were observed. The expression of stem cell surface markers was analyzed by flow cytometry, and expression of cell marker protein was detected by immunofluorescence. SF-MSCs were cultured in osteogenic, adipogenic, and chondrogenic differentiation medium. The differentiation potential of SF-MSCs was analyzed by alkaline phosphatase (Alizarin Red), Oil Red O, and Alcian blue. Antibody detection of human angiogenesis-related proteins was performed compared with bone marrow mesenchymal stem cells (BM-MSCs). The results show that SF-MSCs from the popliteal cyst fluid of pediatric patients showed a shuttle appearance and logarithmic growth. Flow cytometry analysis revealed that SF-MSCs were negative for hematopoietic lineage markers (CD34, CD45) and positive for MSC markers (CD44, CD73, CD90, and CD105). Interstitial cell marker (vimentin) and myofibroblast-like cell marker alpha-smooth muscle actin (α-SMA) were positive. These cells could differentiate into osteogenic, adipogenic, and chondrogenic lineages, respectively. Several types of human angiogenesis-related proteins were detected in the cell secretory fluid. These results show that we successfully obtained SF-MSCs from the popliteal cyst fluid of pediatric patients, which have the potential to be a valuable source of MSCs.

TGase-Enhanced Microtissue Assembly in 3D-Printed-Template-Scaffold (3D-MAPS) for Large Tissue Defect Reparation

Engineering large and functional tissue constructs with complex structures (e.g., external ear or nose) for reparation and reconstruction of tissue defects remains one of the major challenges in regenerative medicine, which demands abundant cell sources, advanced biofabrication schemes, and satisfactory integration with the host for long-term efficacy post implantation. Here the 'Microtissue Assembly in 3D-Printed-template-Scaffold' (3D-MAPS), as a platform technology to rapidly fabricate centimeter-sized functional tissue constructs with complex structures, is developed. 3D-MAPS facilitates bottom-up assembly of large-scale manufactured microtissues within the 3D-printed hollow polymeric templates with pre-defined architectures. The assembly and fusion of 2×10⁶ mesenchymal stem cell-based microtissues within the defined 3D-printed template is further enhanced by addition of a natural protein crosslinker (i.e., transglutaminase (TGase)), and thereby achieves construction of centimeter-sized tissue with high cell viability and mechanical stability in vitro within 30 min. Further in vivo implantation of the 3D-MAPS-fabricated ear-like tissue construct in rabbit models assisted by flap prefabrication technique results in increased structural vascular support and strengthened functional survival. Thus, the TGase-enhanced 3D-MAPS demonstrates its potential and feasibility as a powerful biofabrication platform for tissue engineering application.

Mesenchymal Stem Cell Therapy in Chondral Defects of Knee: Current Concept Review

PURPOSE

Full-thickness cartilage defects if left alone would increase the risk of osteoarthritis (OA) with severe associated pain and functional disability. Articular cartilage defect may result from direct trauma or chronic degeneration. The capability of the mesenchymal stem cells (MSCs) to repair and regenerate cartilage has been widely investigated. This review describes current trends in MSC biology, the sourcing, expansion, application and role of MSCs in chondral defects of human knees.

METHODS

The studies referencing MSCs and knee osteoarthritis were searched (from1998 to 2020) using PubMed, EMBASE, Cochrane Library, Web of Science and the ClinicalTrials.gov with keywords (MSCs, chondral defects or cartilage degeneration of knee, cartilage regeneration, chondrogenesis, tissue engineering, efficacy and safety). The inclusion criteria were based on use of MSCs for treatment of chondral defects and osteoarthritis of the knee, English language and human studies.

RESULTS

The history of MSC research from the initial discovery of their multipotency to the more recent recognition of their role in cartilage defects of knee is elucidated. Several studies have demonstrated promising results in the clinical application for repair of chondral defects as an adjuvant or independent procedure. Intra-articular MSCs provide improvements in pain and function in knee osteoarthritis at short-term follow-up in many studies. The tendency of MSCs to differentiate into fibrocartilage affecting the outcome is a common issue faced by researchers.

CONCLUSION

Some efficacy has been shown of MSCs for cartilage repair in osteoarthritis; however, the evidence of efficacy of intra-articular MSCs on both clinical outcomes and cartilage repair remains limited. Despite the high quality of evidence to support, MSC therapy has emerged but further refinement of methodology will be necessary to support its routine clinical use.

Exosomes derived from human umbilical cord MSCs rejuvenate aged MSCs and enhance their functions for myocardial repair

Background

Age and other cardiovascular risk factors have been reported to impair the activities of mesenchymal stem cells (MSCs), which will affect the efficacy of stem cell transplantation. The objective of the study is to investigate whether exosomes derived from human umbilical cord MSCs (UMSCs) could enhance the activities of bone marrow MSCs from old person (OMSCs), and improve their capacity for cardiac repair.

Methods

Exosomes extracted from conditioned medium of UMSCs were used to treat OMSCs to generate OMSCs^Exo. The key molecule in the exosomes that have potential to rejuvenate aged MSCs were screened, and the role of OMSC was tested in the mouse model of mycardial infarction (MI).

Results

We found the activity of senescence-associated β-galactosidase and the expression of aging-related factors such as p53, p21, and p16 were significantly higher in OMSCs than those in UMSCs. After treatment with UMSC exosomes, these senescence phenotypes of OMSCs were remarkably reduced. The proliferation, migration, differentiation, and anti-apoptotic and paracrine effect were increased in OMSCs^Exo. In vivo study, mice with cardiac infarction had significantly better cardiac function, less fibrosis, and more angiogenesis after they were injected with OMSCs^Exo as compared with those with OMSC. There was more miR-136 expression in UMSCs and OMSCs^Exo than in OMSCs. Upregulation of miR-136 by transfection of miR-136 mimic into OMSCs significantly attenuated the apoptosis and senescence of OMSCs. Apoptotic peptidase activating factor (Apaf1) was found to be the downstream gene that is negatively regulated by miR-136 via directly targeting at its 3′UTR.

Conclusion

Our data suggest that exosomes from young MSCs can improve activities of aged MSCs and enhance their function for myocardial repair by transferring exosomal miR-136 and downregulating Apaf1.

Clinical Application Status of Articular Cartilage Regeneration Techniques: Tissue-Engineered Cartilage Brings New Hope

Hyaline articular cartilage lacks blood vessels, lymphatics, and nerves and is characterised by limited self-repair ability following injury. Traditional techniques of articular cartilage repair and regeneration all have certain limitations. The development of tissue engineering technology has brought hope to the regeneration of articular cartilage. The strategies of tissue-engineered articular cartilage can be divided into three types: “cell-scaffold construct,” cell-free, and scaffold-free. In “cell-scaffold construct” strategies, seed cells can be autologous chondrocytes or stem. Among them, some commercial products with autologous chondrocytes as seed cells, such as BioSeed®-C and CaReS®, have been put on the market and some products are undergoing clinical trials, such as NOVOCART® 3D. The stem cells are mainly pluripotent stem cells and mesenchymal stem cells from different sources. Cell-free strategies that indirectly utilize the repair and regeneration potential of stem cells have also been used in clinical settings, such as TruFit and MaioRegen. Finally, the scaffold-free strategy is also a new development direction, and the short-term repair results of related products, such as NOVOCART® 3D, are encouraging. In this paper, the commonly used techniques of articular cartilage regeneration in surgery are reviewed. By studying different strategies and different seed cells, the clinical application status of tissue-engineered articular cartilage is described in detail.

Mesenchymal stromal cell and bone marrow concentrate therapies for musculoskeletal indications: a concise review of current literature

The interest on applying mesenchymal stromal cells (MSCs) in orthopedic disorders has risen tremendously in the last years due to scientific successes in preclinical in vitro and animal model studies. In a wide range of diseases and injuries of the musculoskeletal system, MSCs are currently under evaluation, but so far have found access to clinical use only in few cases. The current assignment is to translate the acquired knowledge into clinical practice. Therefore, this review aims at presenting a synopsis of the up-to-date status of the use of MSCs and MSC related cell products in musculoskeletal indications. Clinical studies were included, whereas preclinical and animal study data not have been considered. Most studies published so far investigate the final outcome applying bone marrow derived MSCs. In fewer trials the use of adipose tissue derived MSCs and allogenic MSCs was investigated in different applications. Although the reported results are equivocal in the current literature, the vast majority of the studies shows a benefit of MSC based therapies depending on the cell sources and the indication in clinical use. In summary, the clinical use of MSCs in patients in orthopedic indications has been found to be safe. Standardized protocols and clear definitions of the mechanisms of action and the mode and timing of application as well as further coordinated research efforts will be necessary for finally adding MSC based therapies in standard operating procedures and guidelines for the clinicians treating orthopedic disorders.

Dynamic mechanical loading and growth factors influence chondrogenesis of induced pluripotent mesenchymal progenitor cells in a cartilage-mimetic hydrogel

Human induced pluripotent stem cells (iPSCs) have emerged as a promising alternative to bone-marrow derived mesenchymal stem/stromal cells for cartilage tissue engineering. However, the effect of biochemical and mechanical cues on iPSC chondrogenesis remains understudied. This study evaluated chondrogenesis of induced pluripotent mesenchymal progenitor cells (iPS-MPs) encapsulated in a cartilage-mimetic hydrogel under different culture conditions: free swelling versus dynamic compressive loading and different growth factors (TGFβ3 and/or BMP2). Human iPSCs were differentiated into iPS-MPs and chondrogenesis was evaluated by gene expression (qPCR) and protein expression (immunohistochemistry) after three weeks. In pellet culture, both TGFβ3 and BMP2 were required to promote chondrogenesis. However, the hydrogel in growth factor-free conditions promoted chondrogenesis, but rapidly progressed to hypertrophy. Dynamic loading in growth factor-free conditions supported chondrogenesis, but delayed the transition to hypertrophy. Findings were similar with TGFβ3, BMP2, and TGFβ3 + BMP2. Dynamic loading with TGFβ3, regardless of BMP2, was the only condition that promoted a stable chondrogenic phenotype (aggrecan + collagen II) accompanied by collagen X down-regulation. Positive TGFβRI expression with load-enhanced Smad2/3 signaling and low SMAD1/5/8 signaling was observed. In summary, this study reports a promising cartilage-mimetic hydrogel for iPS-MPs that when combined with appropriate biochemical and mechanical cues induces a stable chondrogenic phenotype.

Stem cell-directed therapies for osteoarthritis: The promise and the practice

Osteoarthritis (OA) is a disease of an entire synovial joint characterized by clinical symptoms and distortion of joint tissues, including cartilage, muscles, ligaments, and bone. Although OA is a disease of all joint tissues, it is a defined accessible compartment and is thus amenable to topical surgical and regenerative therapies, including stem cells. All tissues arise from stem progenitor cells, and the relative capacity of different cellular compartments, and different individuals, to renew tissues into adulthood may be important in the onset of many different degenerative diseases. OA is driven by both mechanical and inflammatory factors, but how these factors affect the proliferation and differentiation of cells into cartilage in vivo is largely unknown. Indeed, our very basic understanding of the physiological cellular kinetics and biology of the stem-progenitor cell unit of the articular cartilage, and how this is influenced by mechano-inflammatory injury, is largely unknown. OA seems, rather deceptively, to be the low-hanging fruit for stem cell therapy. Without the basic understanding of the stem cell and progenitor unit that generate and maintain articular cartilage in vivo, we will continue to waste opportunities to both prevent and manage this disease. In this review, we discuss the biology of chondrogenesis, the stem cell populations that support articular cartilage in health and disease, and future opportunities afforded through the translation of basic articular chondrocyte stem cell biology into new clinical therapies.

Characterization of progenitor/stem cell population from human dental socket and their multidifferentiation potential

Dental stem cells have many applications in medicine, dentistry and stem cell biology in general due to their easy accessibility and low morbidity. A common surgical manoeuvre after a tooth extraction is the dental socket curettage which is necessary to clean the alveolus and favour alveolar bone healing. This procedure can cause very low morbidity compared to bone marrow collection procedures and the collected material is normally discarded. In order to investigate if the tissue obtained by dental socket curettage after a tooth extraction was a feasible alternative source to isolate human stem cells, we isolated and characterized two different stem cell populations based on STRO-1 and CD146 expression. We were able to collect and grow cells from dental socket of vital and non-vital teeth. Both populations were proliferative, clonogenic and expressed STRO-1, CD146, CD90, NG2, PDGFR-β, which are markers found in stem cells, presented in vitro multiline-differentiation into osteogenic, chondrogenic, and adipogenic tissue, and in vivo transplanted cells formed mineralized tissue. Interestingly, STRO-1⁺ clonogenic cells presented better multidifferentiation than CD146⁺ cells. Our results showed that mesenchymal stem cells can be isolated from the tiny tissue collected by dental socket curettage after vital and non-vital tooth extraction and suggest that STRO-1 is an important marker to be used to sort cells with multidifferentiation capacity.

Stem cell therapy in pain medicine

Stem cells are attracting attention as a key element in future medicine, satisfying the desire to live a healthier life with the possibility that they can regenerate tissue damaged or degenerated by disease or aging. Stem cells are defined as undifferentiated cells that have the ability to replicate and differentiate themselves into various tissues cells. Stem cells, commonly encountered in clinical or preclinical stages, are largely classified into embryonic, adult, and induced pluripotent stem cells. Recently, stem cell transplantation has been frequently applied to the treatment of pain as an alternative or promising approach for the treatment of severe osteoarthritis, neuropathic pain, and intractable musculoskeletal pain which do not respond to conventional medicine. The main idea of applying stem cells to neuropathic pain is based on the ability of stem cells to release neurotrophic factors, along with providing a cellular source for replacing the injured neural cells, making them ideal candidates for modulating and possibly reversing intractable neuropathic pain. Even though various differentiation capacities of stem cells are reported, there is not enough knowledge and technique to control the differentiation into desired tissues in vivo. Even though the use of stem cells is still in the very early stages of clinical use and raises complicated ethical problems, the future of stem cells therapies is very bright with the help of accumulating evidence and technology.

Hypoxia Activates the PTHrP -MEF2C Pathway to Attenuate Hypertrophy in Mesenchymal Stem Cell Derived Cartilage

Articular cartilage lacks an intrinsic repair capacity and due to the ability of mesenchymal stem cells (MSCs) to differentiate into chondrocytes, MSCs have been touted as a cellular source to regenerate damaged cartilage. However, a number of prevailing concerns for such a treatment remain. Generally, administration of MSCs into a cartilage defect results in poor regeneration of the damaged cartilage with the repaired cartilage consisting primarily of fibro-cartilage rather than hyaline cartilage. Methods that improve the chondrogenic potential of transplanted MSCs in vivo may be advantageous. In addition, the proclivity of MSC-derived cartilage to undergo hypertrophic differentiation or form bone in vivo also remains a clinical concern. If MSC-derived cartilage was to undergo hypertrophic differentiation in vivo, this would be deleterious in a clinical setting. This study focuses on establishing a mechanism of action by which hypoxia or low oxygen tension can be used to both enhance chondrogenesis and attenuate hypertrophic differentiation of both MSC and ATDC5 derived chondrocytes. Having elucidated a novel mechanism of action, the subsequent goals of this study were to develop an in vitro culture regime to mimic the beneficial effects of physiological low oxygen tension in a normoxic environment.

Transplantation of Aggregates of Autologous Synovial Mesenchymal Stem Cells for Treatment of Cartilage Defects in the Femoral Condyle and the Femoral Groove in Microminipigs

BACKGROUND

Previous work has demonstrated that patients with cartilage defects of the knee benefit from arthroscopic transplantation of autologous synovial mesenchymal stem cells (MSCs) in terms of magnetic resonance imaging (MRI), qualitative histologic findings, and Lysholm score. However, the effectiveness was limited by the number of cells obtained, so large-sized defects (>500 mm²) were not investigated. The use of MSC aggregates may enable treatment of larger defects by increasing the number of MSCs adhering to the cartilage defect.

PURPOSE

To investigate whether transplantation of aggregates of autologous synovial MSCs with 2-step surgery could promote articular cartilage regeneration in microminipig osteochondral defects.

STUDY DESIGN

Controlled laboratory study.

METHODS

Synovial MSCs derived from a microminipig were examined for in vitro colony-forming and multidifferentiation abilities. An aggregate of 250,000 synovial MSCs was formed with hanging drop culture, and 16 aggregates (for each defect) were implanted on both osteochondral defects (6 × 6 × 1.5 mm) created in the medial femoral condyle and femoral groove (MSC group). The defects in the contralateral knee were left empty (control group). The knee joints were evaluated at 4 and 12 weeks by macroscopic findings and histology. MRI T1rho mapping images were acquired at 12 weeks. For cell tracking, synovial MSCs were labeled with ferucarbotran before aggregate formation and were observed with MRI at 1 week.

RESULTS

Synovial MSCs showed in vitro colony-forming and multidifferentiation abilities. Regenerative cartilage formation was significantly better in the MSC group than in the control group, as indicated by International Cartilage Repair Society score (macro), modified Wakitani score (histology), and T1rho mapping (biochemical MRI) in the medial condyle at 12 weeks. Implanted cells, labeled with ferucarbotran, were observed in the osteochondral defects at 1 week with MRI. No significant difference was noted in the modified Wakitani score at 4 weeks in the medial condyle and at 4 and 12 weeks in the femoral groove.

CONCLUSION

Transplantation of autologous synovial MSC aggregates promoted articular cartilage regeneration at the medial femoral condyle at 12 weeks in microminipigs.

CLINICAL RELEVANCE

Aggregates of autologous synovial MSCs could expand the indications for cartilage repair with synovial MSCs.

Current Status of Stem Cell Therapies in Tissue Repair and Regeneration

Tissue engineering is a multi-disciplinary field such as material science, life science, and bioengineering that are necessary to make artificial tissue or rejuvenate damaged tissue. Numerous tissue repair techniques and substitute now exist even though it has several shortcomings; these shortcomings give a good reason for the continuous research for more acceptable tissue-engineered substitutes. The search for and use of a suitable stem cell in tissue engineering is a promising concept. Stem cells have a distinctive capability to differentiate and self-renew that make more suitable for cell-based therapies in tissue repair and regeneration. This review article focuses on stem cell for tissue engineering and their methods of manufacture with their application in nerve, bone, skin, cartilage, bladder, cardiac, liver tissue repair and regeneration.

Transplantation of autologous bone marrow-derived mesenchymal stem cells under arthroscopic surgery with microfracture versus microfracture alone for articular cartilage lesions in the knee: A multicenter prospective randomized control clinical trial

Introduction

To investigate the efficacy of the transplantation of autologous bone marrow-derived mesenchymal stem cells (BMSCs) under arthroscopy with microfracture (MFX) compared with microfracture alone.

Methods

Eleven patients with a symptomatic articular cartilage defect of the knee were included in the study. They were randomized to receive BMSCs with MFX (cell-T group, n=7) or MFX alone (control group, n=4). Clinical results were evaluated using International Knee Documentation committee (IKDC) knee evaluation questionnaires and the Knee Injury and Osteoarthritis Outcome Score (KOOS) before and 48 weeks after surgery. Quantitative and qualitative assessments of repair tissue were carried out at 48 weeks by T2 mapping of magnetic resonance images (MRIs) and the magnetic resonance observation of cartilage repair tissue (MOCART) scoring system with follow-up MRI.

Results

No significant differences between preoperative and postoperative IKDC and KOOS were observed in the cell-T or control group. However, forty-eight weeks after surgery, the cell-T group showed a trend for a greater KOOS QOL score compared with the control group (79.4 vs. 39.1, respectively; P=0.07). The T2 value did not differ significantly between the two groups, but the mean MOCART score was significantly higher in the cell-T group than in the control group (P=0.02).

Conclusions

Compared with MFX alone, BMSC transplantation with MFX resulted in better postoperative healing of the cartilage and subchondral bone as determined by the MOCART score. Clinically, BMSC transplantation with MFX gave a higher KOOS QOL score after 48 weeks.

•

This is the first prospective randomized clinical trial between BMSCs with MFX and MFX alone.

•

BMSCs with MFX showed a trend for a greater KOOS QOL score compared with MFX alone.

•

BMSCs with MFX resulted in better healing of the cartilage by the MOCART score.

Articular fibrocartilage - Why does hyaline cartilage fail to repair?

Once damaged, articular cartilage has a limited potential to repair. Clinically, a repair tissue is formed, yet, it is often mechanically inferior fibrocartilage. The use of monolayer expanded versus naïve cells may explain one of the biggest discrepancies in mesenchymal stromal/stem cell (MSC) based cartilage regeneration. Namely, studies utilizing monolayer expanded MSCs, as indicated by numerous in vitro studies, report as a main limitation the induction of type X collagen and hypertrophy, a phenotype associated with endochondral bone formation. However, marrow stimulation and transfer studies report a mechanically inferior collagen I/II fibrocartilage as the main outcome. Therefore, this review will highlight the collagen species produced during the different therapeutic approaches. New developments in scaffold design and delivery of therapeutic molecules will be described. Potential future directions towards clinical translation will be discussed. New delivery mechanisms are being developed and they offer new hope in targeted therapeutic delivery.

Therapeutic Effects of rAAV-Mediated Concomittant Gene Transfer and Overexpression of TGF-β and IGF-I on the Chondrogenesis of Human Bone-Marrow-Derived Mesenchymal Stem Cells

Application of chondroreparative gene vectors in cartilage defects is a powerful approach to directly stimulate the regenerative activities of bone-marrow-derived mesenchymal stem cells (MSCs) that repopulate such lesions. Here, we investigated the ability of combined recombinant adeno-associated virus (rAAV) vector-mediated delivery of the potent transforming growth factor beta (TGF-β) and insulin-like growth factor I (IGF-I) to enhance the processes of chondrogenic differentiation in human MSCs (hMSCs) relative to individual candidate treatments and to reporter (lacZ) gene condition. The rAAV-hTGF-β and rAAV-hIGF-I vectors were simultaneously provided to hMSC aggregate cultures (TGF-β/IGF-I condition) in chondrogenic medium over time (21 days) versus TGF-β/lacZ, IGF-I/lacZ, and lacZ treatments at equivalent vector doses. The cultures were then processed to monitor transgene (co)-overexpression, the levels of biological activities in the cells (cell proliferation, matrix synthesis), and the development of a chondrogenic versus osteogenic/hypertrophic phenotype. Effective, durable co-overexpression of TGF-β with IGF-I via rAAV enhanced the proliferative, anabolic, and chondrogenic activities in hMSCs versus lacZ treatment and reached levels that were higher than those achieved upon single candidate gene transfer, while osteogenic/hypertrophic differentiation was delayed over the period of time evaluated. These findings demonstrate the potential of manipulating multiple therapeutic rAAV vectors as a tool to directly target bone-marrow-derived MSCs in sites of focal cartilage defects and to locally enhance the endogenous processes of cartilage repair.