Adipose-Derived Mesenchymal Stem Cells for the Treatment of Articular Cartilage: A Systematic Review on Preclinical and Clinical Evidence

No evidence for combining cartilage treatment and knee osteotomy in osteoarthritic joints: a systematic literature review

PURPOSE

To assess whether the combination of HTO and cartilage treatment produced an additional clinical benefit compared to HTO alone. The secondary aim was to identify if there was any difference among different cartilage procedures in terms of healing potential and clinical outcome.

METHODS

A systematic review of the literature was performed on PubMed database by three independent observers according to the following inclusion criteria: clinical reports of any level of evidence, written in the English language, with no time limitation, about HTO associated with cartilage surgical and injective treatment, including surveys reporting clinical, radiological, or second-look outcomes at any follow-up time.

RESULTS

The database search identified 1956 records: 21 studies were included for the final analysis, for a total of 1068 patients; 10 case series and 11 comparative studies. While overall good results were reported in the case series, the analysis of the comparative studies showed less uniform results. Among the eight studies investigating HTO with cartilage surgical procedures, improved tissue regeneration was found in 5/8 studies, whereas a clinical improvement was reported only in two studies. Three studies on HTO combination with injective treatment showed better tissue regeneration and clinical benefit.

CONCLUSIONS

Literature presents low-quality studies, with only few heterogeneous comparative papers. While surgical treatments targeting only the cartilage layer did not achieve clinical improvements, injective treatments targeting the overall joint environment showed promising findings. This prompts further research towards the development of treatments able to improve knee osteotomies outcomes. However, until new evidence will prove otherwise, there is no indication for a combined cartilage treatment in routine clinical practice.

LEVEL OF EVIDENCE

Level IV.

Concentrated adipose tissue infusion for the treatment of knee osteoarthritis: clinical and histological observations

PURPOSE

Osteoarthritis (OA) is characterized by articular cartilage degeneration and subchondral bone sclerosis. OA can benefit of non-surgical treatments with collagenase-isolated stromal vascular fraction (SVF) or cultured-expanded mesenchymal stem cells (ASCs). To avoid high manipulation of the lipoaspirate needed to obtain ASCs and SVF, we investigated whether articular infusions of autologous concentrated adipose tissue are an effective treatment for knee OA patients.

METHODS

The knee of 20 OA patients was intra-articularly injected with autologous concentrated adipose tissue, obtained after centrifugation of lipoaspirate. Patients' articular functionality and pain were evaluated by VAS and WOMAC scores at three, six and 18 months from infusion. The osteogenic and chondrogenic ability of ASCs contained in the injected adipose tissue was studied in in vitro primary osteoblast and chondrocyte cell cultures, also plated on 3D-bone scaffold. Knee articular biopsies of patients previously treated with adipose tissue were analyzed. Immunohistochemistry (IHC) and scanning electron microscopy (SEM) were performed to detect cell differentiation and tissue regeneration.

RESULTS

The treatment resulted safe, and all patients reported an improvement in terms of pain reduction and increase of function. According to the osteogenic or chondrogenic stimulation, ASCs expressed alkaline phosphatase or aggrecan, respectively. The presence of a layer of newly formed tissue was visualized by IHC staining and SEM. The biopsy of previously treated knee joints showed new tissue formation, starting from the bone side of the osteochondral lesion.

CONCLUSIONS

Overall our data indicate that adipose tissue infusion stimulates tissue regeneration and might be considered a safe treatment for knee OA.

Advances in stem cell therapy for cartilage regeneration in osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a progressive joint disease that compromises the structural integrity of cartilage tissue. Conventional treatments based on medication or surgery are nowadays inefficient and cell-based therapy has emerged as one of the most promising methods for cartilage regeneration. The first therapy developed for cartilage defects was autologous chondrocyte implantation, but in the last few decades stem cells (SCs) from different sources have been proposed as a possible alternative for OA.

AREAS COVERED

SC sources and available delivery procedures (scaffolds/hydrogels) are presented, along with the main issues arisen in this regard. Thereafter, preclinical and clinical trials performed in recent years are reviewed in order to take a glance toward the potential benefits that such therapies could deliver to the patients.

EXPERT OPINION

SCs have proven their potential and safety for OA treatment. Nevertheless, there are still many questions to be resolved before their widespread used in clinical practice, such as the treatment mechanism, the best cell source, the most appropriate processing method, the most effective dose and delivery procedure, and their efficacy. In this sense, long-term follow-up and larger randomized controlled trials utilizing standardized and established outcome scores are mandatory to make objective conclusions.

Synergistic Effects of FGF-18 and TGF-β3 on the Chondrogenesis of Human Adipose-Derived Mesenchymal Stem Cells in the Pellet Culture

Cell-based therapy serves as an effective way for cartilage repair. Compared with a limited source of autologous chondrocytes, adipose-derived stem cells (ADSCs) are proposed as an attractive cell source for cartilage regeneration. How to drive chondrogenic differentiation of ADSCs efficiently remains to be further investigated. TGF-β3 has shown a strong chondrogenic action on ADSCs. Recently, fibroblast growth factor 18 (FGF-18) has gained marked attention due to its anabolic effects on cartilage metabolism, but existing data regarding the role of FGF-18 on the chondrogenic potential of mesenchymal stem cells (MSCs) are conflicting. In addition, whether the combined application of FGF-18 and TGF-β3 would improve the efficiency of the chondrogenic potential of ADSCs has not been thoroughly studied. In the current study, we isolated human ADSCs and characterized the expression of their surface antigens. Also, we evaluated the chondrogenic potential of FGF-18 on ADSCs using an in vitro pellet model by measuring glycosaminoglycan (GAG) content, collagen level, histologic appearance, and expression of cartilage-related genes. We found that FGF-18, similarly to TGF-β3, had a positive impact on chondrogenic differentiation and matrix deposition when presented throughout the culture period. More importantly, we observed synergistic effects of FGF-18 and TGF-β3 on the chondrogenic differentiation of ADSCs in the in vitro pellet model. Our results provide critical information on the therapeutic use of ADSCs with the help of FGF-18 and TGF-β3 for cartilage regeneration.

Adipose-Derived Stromal Vascular Fraction/Xenohybrid Bone Scaffold: An Alternative Source for Bone Regeneration

Adipose tissue-derived stem cells (ASCs) are a promising tool for the treatment of bone diseases or skeletal lesions, thanks to their ability to potentially repair damaged tissue. One of the major limitations of ASCs is represented by the necessity to be isolated and expanded through in vitro culture; thus, a strong interest was generated by the adipose stromal vascular fraction (SVF), the noncultured fraction of ASCs. SVF is a heterogeneous cell population, directly obtained after collagenase treatment of adipose tissue. In order to investigate and compare the bone-regenerative potential of SVF and ASCs, they were plated on SmartBone®, a xenohybrid bone scaffold, already used in clinical practice with successful results. We showed that SVF plated on SmartBone, in the presence of osteogenic factors, had better osteoinductive capabilities than ASCs, in terms of differentiation into bone cells, mineralization, and secretion of soluble factors stimulating osteoblasts. Indeed, we observed an increasing area of new tissue over time, with and without OM. These data strongly support an innovative idea for the use of adipose SVF and bone scaffolds to promote tissue regeneration and repair, also thanks to an easier cell management preparation that allows a potentially larger use in clinical applications.

Arthroscopic Synovectomy Combined with Autologous Fat Grafting in Early Stages of CMC Osteoarthritis of the Thumb

Background  Minimal invasive treatments such as arthroscopic techniques may be adequate to restore the anatomy and functional integrity of the thumb CMC (carpometacarpal) joint. In this paper, we reported the interposition of autologous fat tissue in combination with arthroscopic synovectomy/debridement for early stage of the thumb CMC joint osteoarthritis. Patients and Methods  Twelve patients with a mean age of 46 years with early radiological stages of thumb CMC joint osteoarthritis were included. Evaluation of outcome was measured prior and 3, 12, and 24 months after surgery including, Visual Analog Scale (VAS), QuickDASH, grip and pinch strength, range of motion (ROM), and patient satisfaction. Results  Pain at rest (or with load) was reduced from preoperative 4,7 (8,7) to 2 (5,9) at 3 to 6 months; 1,4 (4,3) at 12 months; and 0,75 (2,7) at 2 years after the surgery. Initial preoperative QuickDASH value of 52 points reduced to 33 (17-65) at 6 months, 23 (2-70) at 12 months, and 20 (11-29) at 24 months after the surgery. Grip strength and thumb pinch with respect to the contralateral untreated thumb was reduced in the first 12 months but recovered subsequently. ROM was equal to the contralateral thumb. Three patients suffered from tendinitis and required surgical treatment. One patient indicated prolonged pain symptoms. No infections were noted and no donor-site morbidity or side effects were detected. Conclusion  Arthroscopic synovectomy combined with autologous fat graft is a reliable surgical option for early thumb CMC joint osteoarthritis and that effect continues for more than 24 months.

Combating Osteoarthritis through Stem Cell Therapies by Rejuvenating Cartilage: A Review

Knee osteoarthritis (OA) is a chronic degenerative disorder which could be distinguished by erosion of articular cartilage, pain, stiffness, and crepitus. Not only aging-associated alterations but also the metabolic factors such as hyperglycemia, dyslipidemia, and obesity affect articular tissues and may initiate or exacerbate the OA. The poor self-healing ability of articular cartilage due to limited regeneration in chondrocytes further adversely affects the osteoarthritic microenvironment. Traditional and current surgical treatment procedures for OA are limited and incapable to reverse the damage of articular cartilage. To overcome these limitations, cell-based therapies are currently being employed to repair and regenerate the structure and function of articular tissues. These therapies not only depend upon source and type of stem cells but also on environmental conditions, growth factors, and chemical and mechanical stimuli. Recently, the pluripotent and various multipotent mesenchymal stem cells have been employed for OA therapy, due to their differentiation potential towards chondrogenic lineage. Additionally, the stem cells have also been supplemented with growth factors to achieve higher healing response in osteoarthritic cartilage. In this review, we summarized the current status of stem cell therapies in OA pathophysiology and also highlighted the potential areas of further research needed in regenerative medicine.

Translational Application of Microfluidics and Bioprinting for Stem Cell-Based Cartilage Repair

Cartilage defects can impair the most elementary daily activities and, if not properly treated, can lead to the complete loss of articular function. The limitations of standard treatments for cartilage repair have triggered the development of stem cell-based therapies. In this scenario, the development of efficient cell differentiation protocols and the design of proper biomaterial-based supports to deliver cells to the injury site need to be addressed through basic and applied research to fully exploit the potential of stem cells. Here, we discuss the use of microfluidics and bioprinting approaches for the translation of stem cell-based therapy for cartilage repair in clinics. In particular, we will focus on the optimization of hydrogel-based materials to mimic the articular cartilage triggered by their use as bioinks in 3D bioprinting applications, on the screening of biochemical and biophysical factors through microfluidic devices to enhance stem cell chondrogenesis, and on the use of microfluidic technology to generate implantable constructs with a complex geometry. Finally, we will describe some new bioprinting applications that pave the way to the clinical use of stem cell-based therapies, such as scaffold-free bioprinting and the development of a 3D handheld device for the in situ repair of cartilage defects.

The Utility of Biologics, Osteotomy, and Cartilage Restoration in the Knee

The management of complex cartilage and meniscal pathology in young, athletic patients is extremely challenging. Joint preservation surgery is most difficult in patients with concomitant knee pathologies, including cartilage defects, meniscal deficiency, malalignment, and/or ligamentous insufficiency. Clinical decision making for these patients is further complicated by articular cartilage lesions, which often are incidental findings; therefore, treatment decisions must be based on the confirmed contribution of articular cartilage lesions to symptomatology. Surgical management of any of the aforementioned knee pathologies that is performed in isolation typically results in acceptable patient outcomes; however, concomitant procedures for the management of concomitant knee pathologies often are essential to the success of any single procedure. The use of biologic therapy as an alternative to or to augment more conventional surgical management has increased in popularity in the past decade, and indications for biologic therapy continue to evolve. Orthopaedic surgeons should understand knee joint preservation techniques, including biologic and reconstructive approaches in young, high-demand patients.

Modulation of Gene Expression in Infrapatellar Fat Pad-Derived Mesenchymal Stem Cells in Osteoarthritis

Aim In the osteoarthritis (OA) disease, all structures of the joint are involved. The infrapatellar Hoffa fat pad is rich in macrophages and granulocytes, which also represents a source of adipose mesenchymal progenitor cells (ASC) cells. In our study, we analyze how OA affects the ability of ASC-derived from Hoffa's fat pad to differentiate into chondrocytes. Material and methodology We took knee Hoffa's pad samples and adipose tissue from the proximal thigh from 6 patients diagnosed with severe OA and from another 6 patients with an anterior cruciate ligament (ACL) rupture without OA. From all the patients, we took subcutaneous adipose tissue from the thigh, as the control group. Samples of synovial fluid (SF) were also extracted. The gene expression was analyzed by real-time quantitative polymerase chain reaction. Results PTH1R and MMP13 expression during chondrogenic differentiation were similar between OA and ACL groups, while the expression of OPG, FGF2, TGFβ, MMP3 were significantly lower in the OA group. Exposure of differentiated ASC to OA SF induced an increase in the expression of OPG, PTH1R, and MMP13 and a decrease in the expression of FGF2 in cell culture of the ACL group. However, expression of none of these factors was altered by the OA synovial fluid in ASC cells of the OA group. Conclusion OA of the knee also affects the mesenchymal stem cells of Hoffa fat, suggesting that Hoffa fat is a new actor in the OA degenerative process that can contribute to the origin, onset, and progression of the disease.

Magnetic Targeted Delivery of Induced Pluripotent Stem Cells Promotes Articular Cartilage Repair

Cartilage regeneration treatments using stem cells are associated with problems due to the cell source and the difficulty of delivering the cells to the cartilage defect. We consider labeled induced pluripotent stem (iPS) cells to be an ideal source of cells for tissue regeneration, and if iPS cells could be delivered only into cartilage defects, it would be possible to repair articular cartilage. Consequently, we investigated the effect of magnetically labeled iPS (m-iPS) cells delivered into an osteochondral defect by magnetic field on the repair of articular cartilage. iPS cells were labeled magnetically and assessed for maintenance of pluripotency by their ability to form embryoid bodies in vitro and to form teratomas when injected subcutaneously into nude rats. These cells were delivered specifically into cartilage defects in nude rats using a magnetic field. The samples were graded according to the histologic grading score for cartilage regeneration. m-iPS cells differentiated into three embryonic germ layers and formed teratomas in the subcutaneous tissue. The histologic grading score was significantly better in the treatment group compared to the control group. m-iPS cells maintained pluripotency, and the magnetic delivery system proved useful and safe for cartilage repair using iPS cells.

Arthroscopic Harvest of Adipose-Derived Mesenchymal Stem Cells From the Infrapatellar Fat Pad

BACKGROUND

The successful isolation of adipose-derived mesenchymal stem cells (ADSCs) from the arthroscopically harvested infrapatellar fat pad (IFP) would provide orthopaedic surgeons with an autologous solution for regenerative procedures.

PURPOSE

To demonstrate the quantity and viability of the mesenchymal stem cell population arthroscopically harvested from the IFP as well as the surrounding synovium.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The posterior border of the IFP, including the surrounding synovial tissue, was harvested arthroscopically from patients undergoing anterior cruciate ligament reconstruction. Tissue was then collected in an AquaVage adipose canister, followed by fat fractionization using syringe emulsification and concentration with an AdiPrep device. In the laboratory, the layers of tissue were separated and then digested with 0.3% type I collagenase. The pelleted stromal vascular fraction (SVF) cells were then immediately analyzed for viability, mesenchymal cell surface markers by fluorescence-activated cell sorting, and clonogenic capacity. After culture expansion, the metabolic activity of the ADSCs was assessed by an AlamarBlue assay, and the multilineage differentiation capability was tested. The transition of surface antigens from the SVF toward expanded ADSCs at passage 2 was further evaluated.

RESULTS

SVF cells were successfully harvested with a mean yield of 4.86 ± 2.64 × 10⁵ cells/g of tissue and a mean viability of 69.03% ± 10.75%, with ages ranging from 17 to 52 years (mean, 35.14 ± 13.70 years; n = 7). The cultured ADSCs composed a mean 5.85% ± 5.89% of SVF cells with a mean yield of 0.33 ± 0.42 × 10⁵ cells/g of tissue. The nonhematopoietic cells (CD45^-) displayed the following surface antigens as a percentage of the viable population: CD44⁺ (52.21% ± 4.50%), CD73⁺CD90⁺CD105⁺ (19.20% ± 17.04%), and CD44⁺CD73⁺CD90⁺CD105⁺ (15.32% ± 15.23%). There was also a significant increase in the expression of ADSC markers CD73 (96.97% ± 1.72%; P < .01), CD10 (84.47% ± 15.46%; P < .05), and CD166 (11.63% ± 7.84%; P < .005) starting at passage 2 compared with freshly harvested SVF cells. The clonogenic efficiency of SVF cells was determined at a mean 3.21% ± 1.52% for layer 1 and 1.51% ± 0.55% for layer 2. Differentiation into cartilage, fat, and bone tissue was demonstrated by tissue-specific staining and quantitative polymerase chain reaction.

CONCLUSION

SVF cells from the IFP and adjacent synovial tissue were successfully harvested using an arthroscopic technique and produced ADSCs with surface markers that meet criteria for defined mesenchymal stem cells.

CLINICAL RELEVANCE

An autologous source of stem cells can now be harvested using a simple arthroscopic technique that will allow orthopaedic surgeons easier access to progenitor cells for regenerative procedures.

Is there a role for stem cells in treating articular injury?

Articular cartilage is a specialized tissue with a high prevalence of injuries. The complex architecture of articular cartilage means that injuries are difficult to treat. The sequelae of such injuries include post-traumatic osteoarthritis. Current treatments include microfracture, microdrilling, osteochondral transplantation and matrix autologous chondral implantation. However, current surgical therapies have a number of disadvantages. Mesenchymal stem cells have been suggested as a potential alternative therapy, with a theoretical ability to regenerate articular cartilage. Research, although positive, is mainly limited to case series, in which the follow up is short to medium term. Stem cells may hold the answer to the age-old problem of articular cartilage injury but more robust evidence is required.

Adipose-derived stromal cell in regenerative medicine: A review

The application of appropriate cell origin for utilizing in regenerative medicine is the major issue. Various kinds of stem cells have been used for the tissue engineering and regenerative medicine. Such as, several stromal cells have been employed as treat option for regenerative medicine. For example, human bone marrow-derived stromal cells and adipose-derived stromal cells (ADSCs) are used in cell-based therapy. Data relating to the stem cell therapy and processes associated with ADSC has developed remarkably in the past 10 years. As medical options, both the stromal vascular and ADSC suggests good opportunity as marvelous cell-based therapeutics. The some biological features are the main factors that impact the regenerative activity of ADSCs, including the modulation of the cellular immune system properties and secretion of bioactive proteins such as cytokines, chemokines and growth factors, as well as their intrinsic anti-ulcer and anti-inflammatory potential. A variety of diseases have been treated by ADSCs, and it is not surprising that there has been great interest in the possibility that ADSCs might be used as therapeutic strategy to improve a wider range of diseases. This is especially important when it is remembered that routine therapeutic methods are not completely effective in treat of diseases. Here, it was discuss about applications of ADSC to colitis, liver failure, diabetes mellitus, multiple sclerosis, orthopaedic disorders, hair loss, fertility problems, and salivary gland damage.

The Good the Bad and the Ugly of Glycosaminoglycans in Tissue Engineering Applications

High sulfation, low cost, and the status of heparin as an already FDA- and EMA- approved product, mean that its inclusion in tissue engineering (TE) strategies is becoming increasingly popular. However, the use of heparin may represent a naïve approach. This is because tissue formation is a highly orchestrated process, involving the temporal expression of numerous growth factors and complex signaling networks. While heparin may enhance the retention and activity of certain growth factors under particular conditions, its binding 'promiscuity' means that it may also inhibit other factors that, for example, play an important role in tissue maintenance and repair. Within this review we focus on articular cartilage, highlighting the complexities and highly regulated processes that are involved in its formation, and the challenges that exist in trying to effectively engineer this tissue. Here we discuss the opportunities that glycosaminoglycans (GAGs) may provide in advancing this important area of regenerative medicine, placing emphasis on the need to move away from the common use of heparin, and instead focus research towards the utility of specific GAG preparations that are able to modulate the activity of growth factors in a more controlled and defined manner, with less off-target effects.

Adipose, Bone Marrow and Synovial Joint-Derived Mesenchymal Stem Cells for Cartilage Repair

Current cell-based repair strategies have proven unsuccessful for treating cartilage defects and osteoarthritic lesions, consequently advances in innovative therapeutics are required and mesenchymal stem cell-based (MSC) therapies are an expanding area of investigation. MSCs are capable of differentiating into multiple cell lineages and exerting paracrine effects. Due to their easy isolation, expansion, and low immunogenicity, MSCs are an attractive option for regenerative medicine for joint repair. Recent studies have identified several MSC tissue reservoirs including in adipose tissue, bone marrow, cartilage, periosteum, and muscle. MSCs isolated from these discrete tissue niches exhibit distinct biological activities, and have enhanced regenerative potentials for different tissue types. Each MSC type has advantages and disadvantages for cartilage repair and their use in a clinical setting is a balance between expediency and effectiveness. In this review we explore the challenges associated with cartilage repair and regeneration using MSC-based cell therapies and provide an overview of phenotype, biological activities, and functional properties for each MSC population. This paper also specifically explores the therapeutic potential of each type of MSC, particularly focusing on which cells are capable of producing stratified hyaline-like articular cartilage regeneration. Finally we highlight areas for future investigation. Given that patients present with a variety of problems it is unlikely that cartilage regeneration will be a simple "one size fits all," but more likely an array of solutions that need to be applied systematically to achieve regeneration of a biomechanically competent repair tissue.

Basic science of osteoarthritis

Osteoarthritis (OA) is a prevalent, disabling disorder of the joints that affects a large population worldwide and for which there is no definitive cure. This review provides critical insights into the basic knowledge on OA that may lead to innovative end efficient new therapeutic regimens. While degradation of the articular cartilage is the hallmark of OA, with altered interactions between chondrocytes and compounds of the extracellular matrix, the subchondral bone has been also described as a key component of the disease, involving specific pathomechanisms controlling its initiation and progression. The identification of such events (and thus of possible targets for therapy) has been made possible by the availability of a number of animal models that aim at reproducing the human pathology, in particular large models of high tibial osteotomy (HTO). From a therapeutic point of view, mesenchymal stem cells (MSCs) represent a promising option for the treatment of OA and may be used concomitantly with functional substitutes integrating scaffolds and drugs/growth factors in tissue engineering setups. Altogether, these advances in the fundamental and experimental knowledge on OA may allow for the generation of improved, adapted therapeutic regimens to treat human OA.

Adipose Derived-Mesenchymal Stem Cells Viability and Differentiating Features for Orthopaedic Reparative Applications: Banking of Adipose Tissue

Osteoarthritis is characterized by loss of articular cartilage also due to reduced chondrogenic activity of mesenchymal stem cells (MSCs) from patients. Adipose tissue is an attractive source of MSCs (ATD-MSCs), representing an effective tool for reparative medicine, particularly for treatment of osteoarthritis, due to their chondrogenic and osteogenic differentiation capability. The treatment of symptomatic knee arthritis with ATD-MSCs proved effective with a single infusion, but multiple infusions could be also more efficacious. Here we studied some crucial aspects of adipose tissue banking procedures, evaluating ATD-MSCs viability, and differentiation capability after cryopreservation, to guarantee the quality of the tissue for multiple infusions. We reported that the presence of local anesthetic during lipoaspiration negatively affects cell viability of cryopreserved adipose tissue and cell growth of ATD-MSCs in culture. We observed that DMSO guarantees a faster growth of ATD-MSCs in culture than trehalose. At last, ATD-MSCs derived from fresh and cryopreserved samples at -80°C and -196°C showed viability and differentiation ability comparable to fresh samples. These data indicate that cryopreservation of adipose tissue at -80°C and -196°C is equivalent and preserves the content of ATD-MSCs in Stromal Vascular Fraction (SVF), guaranteeing the differentiation ability of ATD-MSCs.

Adipose-Derived Stem Cells Respond to Increased Osmolarities

Cell therapies present a feasible option for the treatment of degenerated cartilaginous and intervertebral disc (IVD) tissues. Microenvironments of these tissues are specific and often differ from the microenvironment of cells that, could be potentially used for therapy, e.g. human adipose-derived stem cells (hASC). To ensure safe and efficient implantation of hASC, it is important to evaluate how microenvironmental conditions at the site of implantation affect the implanted cells. This study has demonstrated that cartilaginous tissue-specific osmolarities ranging from 400-600 mOsm/L affected hASC in a dose- and time-dependent fashion in comparison to 300 mOsm/L. Increased osmolarities resulted in transient (nuclear DNA and actin reorganisation) and non-transient, long-term morphological changes (vesicle formation, increase in cell area, and culture morphology), as well as reduced proliferation in monolayer cultures. Increased osmolarities diminished acid proteoglycan production and compactness of chondrogenically induced pellet cultures, indicating decreased chondrogenic potential. Viability of hASC was strongly dependent on the type of culture, with hASC in monolayer culture being more tolerant to increased osmolarity compared to hASC in suspension, alginate-agarose hydrogel, and pellet cultures, thus emphasizing the importance of choosing relevant in vitro conditions according to the specifics of clinical application.

Neo-cartilage engineered from primary chondrocytes is epigenetically similar to autologous cartilage, in contrast to using mesenchymal stem cells

OBJECTIVES

To compare the epigenetic landscape of 3D cell models of human primary articular chondrocytes (hPACs) and human bone-marrow derived mesenchymal stem cells (hBMSCs) and their respective autologous articular cartilage.

DESIGN

Using Illumina Infinium HumanMethylation450 BeadChip arrays, the DNA methylation landscape of the different cell sources and autologous cartilage was determined. Pathway enrichment was analyzed using DAVID.

RESULTS

Principal Component Analysis (PCA) of methylation data revealed separate clustering of hBMSC samples. Between hBMSCs and autologous cartilage 86,881 cytosine-phosphate-guanine dinucleotides (CpGs) (20.2%), comprising 3,034 differentially methylated regions (DMRs; Δβ > 0.1; with the same direction of effect), were significantly differentially methylated. In contrast, between hPACs and autologous cartilage only 5,706 CpGs (1.33%) were differentially methylated. Of interest was the finding of the transcriptionally active, hyper-methylation of a Cartilage Intermediate Layer Protein (CILP) annotated DMR (Δβ = 0.16) in PAC-cartilage, corresponding to a profound decrease in CILP expression after in vitro culturing of hPACs as compared to autologous cartilage.

CONCLUSIONS

In vitro engineered neo-cartilage tissue from primary chondrocytes, hPACs, exhibits a DNA methylation landscape that is almost identical (99% similarity) to autologous cartilage, in contrast to neo-cartilage engineered from bone marrow-derived mesenchymal stem cells (MSCs). Although hBMSCs are widely used for cartilage engineering purposes the effects of these vast differences on cartilage regeneration and long term consequences of implantation, are not known. The use of hBMSCs or hPACs for future cartilage tissue regeneration purposes should therefore be investigated in more depth in future endeavors to better understand the consequences of the differential methylome on neo-cartilage.

Biological Treatments for Tendon and Ligament Abnormalities: A Critical Analysis Review

The poor intrinsic healing potential of tendon and ligamentous tissue has driven the search for biological agents that can improve healing, most notably platelet-rich plasma (PRP) and autologous stem cells. Current evidence best supports the use of PRP as treatment for chronic, degenerative tendinopathies such as lateral epicondylitis of the elbow or patellar tendinopathy. It does not support the use of PRP to promote tendon or ligament-to-bone healing in rotator cuff repair or anterior cruciate ligament (ACL) reconstruction. Clinical evidence regarding the use of autologous stem cells as treatment for tendon and ligament abnormalities is currently limited. However, the initial results appear to be promising, particularly following rotator cuff repair. A major limitation in the evaluation of current data is the lack of standardization in the preparation and composition of PRP, which are often not reported. Future investigators should make an effort to report the method of preparation and final composition of PRP used. Autologous stem cells were most often harvested from bone marrow aspirate but were occasionally derived from dermal tenocyte cells. Recent studies have explored new sources for stem cells, including adipose tissue, peripheral blood, and human amniotic tissue. We expect that clinical data evaluating these treatments will soon emerge.

Non-surgical treatments for the management of early osteoarthritis

Non-surgical treatments are usually the first choice for the management of knee degeneration, especially in the early osteoarthritis (OA) phase when no clear lesions or combined abnormalities need to be addressed surgically. Early OA may be addressed by a wide range of non-surgical approaches, from non-pharmacological modalities to dietary supplements and pharmacological therapies, as well as physical therapies and novel biological minimally invasive procedures involving injections of various substances to obtain a clinical improvement and possibly a disease-modifying effect. Numerous pharmaceutical agents are able to provide clinical benefit, but no one has shown all the characteristic of an ideal treatment, and side effects have been reported at both systemic and local level. Patients and physicians should have realistic outcome goals in pharmacological treatment, which should be considered together with other conservative measures. Among these, exercise is an effective conservative approach, while physical therapies lack literature support. Even though a combination of these therapeutic options might be the most suitable strategy, there is a paucity of studies focusing on combining treatments, which is the most common clinical scenario. Further studies are needed to increase the limited evidence on non-surgical treatments and their combination, to optimize indications, application modalities, and results with particular focus on early OA. In fact, most of the available evidence regards established OA. Increased knowledge about degeneration mechanisms will help to better target the available treatments and develop new biological options, where preliminary results are promising, especially concerning early disease phases. Specific treatments aimed at improving joint homoeostasis, or even counteracting tissue damage by inducing regenerative processes, might be successful in early OA, where tissue loss and anatomical changes are still at very initial stages.

Stem cells in articular cartilage regeneration

Mesenchymal stem cells (MSCs) have emerged as a promising option to treat articular defects and early osteoarthritis (OA) stages. However, both their potential and limitations for a clinical use remain controversial. Thus, the aim of this systematic review was to examine MSCs treatment strategies in clinical settings, in order to summarize the current evidence of their efficacy for the treatment of cartilage lesions and OA.Among the 60 selected studies, 7 were randomized, 13 comparative, 31 case series, and 9 case reports; 26 studies reported the results after injective administration, whereas 33 used surgical implantation. One study compared the two different modalities. With regard to the cell source, 20 studies concerned BMSCs, 17 ADSCs, 16 BMC, 5 PBSCs, 1 SDSCs, and 1 compared BMC versus PBSCs. Overall, despite the increasing literature on this topic, the evidence is still limited, in particular for high-level studies. On the other hand, the available studies allow to draw some indications. First, no major adverse events related to the treatment or to the cell harvest have been reported. Second, a clinical benefit of using MSCs therapies has been reported in most of the studies, regardless of cell source, indication, or administration method. This effectiveness has been reflected by clinical improvements and also positive MRI and macroscopic findings, whereas histologic features gave more controversial results among different studies. Third, young age, lower BMI, smaller lesion size for focal lesions, and earlier stages of OA joints have been shown to correlate with better outcomes, even though the available data strength does not allow to define clear cutoff values. Finally, definite trends can be observed with regard to the delivery method: currently cultured cells are mostly being administered by i.a. injection, while one-step surgical implantation is preferred for cell concentrates. In conclusion, while promising results have been shown, the potential of these treatments should be confirmed by reliable clinical data through double-blind, controlled, prospective and multicenter studies with longer follow-up, and specific studies should be designed to identify the best cell sources, manipulation, and delivery techniques, as well as pathology and disease phase indications.

Adipose stem cells differentiated chondrocytes regenerate damaged cartilage in rat model of osteoarthritis

Transplantation of mesenchymal stem cells (MSCs) or autologous chondrocytes has been shown to repair damages to articular cartilage due to osteoarthritis (OA). However, survival of transplanted cells is considerably reduced in the osteoarthritic environment and it affects successful outcome of the transplantation of the cells. Differentiated chrondroytes derived from adipose stem cells have been proposed as an alternative source and our study investigated this possibility in rats. We investigated the regenerative potential of ADSCs and DCs in osteoarthritic environment in the repair of cartilage in rats. We found that ADSCs maintained fibroblast morphology in vitro and also expressed CD90 and CD29. Furthermore, ADSCs differentiated into chondrocytes, accompanied by increased level of proteoglycans and expression of chondrocytes specific genes, such as, Acan, and Col2a1. Histological examination of transplanted knee joints showed regeneration of cartilage tissue compared to control OA knee joints. Increase in gene expression for Acan, Col2a1 with concomitant decrease in the expression of Col1a1 suggested formation of hyaline like cartilage. A significant increase in differentiation index was observed in DCs and ADSCs transplanted knee joints (P = 0.0110 vs. P = 0.0429) when compared to that in OA control knee joints. Furthermore, transplanted DCs showed increased proliferation along with reduction in apoptosis as compared to untreated control. In conclusion, DCs showed better survival and regeneration potential as compared with ADSCs in rat model of OA and thus may serve a better option for regeneration of osteoarthritic cartilage.

Gata2 Is a Rheostat for Mesenchymal Stem Cell Fate in Male Mice

Gata2 is a zinc finger transcription factor that is important in hematopoiesis and neuronal development. However, the roles of Gata2 in the mesenchymal lineages are poorly understood. In vitro studies suggest that Gata2 modulates adipocyte differentiation and mesenchymal stem cell (MSC) proliferation. To systematically determine the in vivo functions of Gata2 in the MSC lineage commitment and development, we have generated three mouse models in which Gata2 is specifically deleted in MSCs, adipocytes, or osteoblasts. During the MSC expansion stage, Gata2 promotes proliferation and attenuates differentiation; thereby Gata2 loss in MSCs results in enhanced differentiation of both adipocytes and osteoblasts. During the differentiation stage, Gata2 also plays MSC-independent roles to impede lineage commitment; hence, Gata2 loss in adipocyte or osteoblast lineages also augments adipogenesis and osteoblastogenesis, respectively. These findings reveal Gata2 as a crucial rheostat of MSC fate to control osteoblast and adipocyte lineage development.