Modulation of Hyaluronan Synthesis by the Interaction between Mesenchymal Stem Cells and Osteoarthritic Chondrocytes

Mesenchymal stromal cell-based therapy for cartilage regeneration in knee osteoarthritis

Osteoarthritis, as a degenerative disease, is a common problem and results in high socioeconomic costs and rates of disability. The most commonly affected joint is the knee and characterized by progressive destruction of articular cartilage, loss of extracellular matrix, and progressive inflammation. Mesenchymal stromal cell (MSC)-based therapy has been explored as a new regenerative treatment for knee osteoarthritis in recent years. However, the detailed functions of MSC-based therapy and related mechanism, especially of cartilage regeneration, have not been explained. Hence, this review summarized how to choose, authenticate, and culture different origins of MSCs and derived exosomes. Moreover, clinical application and the latest mechanistical findings of MSC-based therapy in cartilage regeneration were also demonstrated.

Enhanced expression of hyaluronic acid in osteoarthritis-affected knee-cartilage chondrocytes during three-dimensional in vitro culture in a hyaluronic-acid-retaining polymer scaffold

BACKGROUND

Chondrocyte transplantation to address cartilage damage is an established solution. Because hyaluronic acid (HA) is an essential component for homeostasis of the cartilage, in order to arrive at methodologies to utilize its advantages in cell-based therapies, we compared the HA retention capability of a thermoreversible gelation polymer scaffold-based environment (3D-TGP) with conventional in vitro cell culture methodologies.

METHODS

Chondrocytes derived from osteoarthritis-affected knee joint cartilage of elderly patients were used and accomplished in three phases. In Phase I, the levels of HA secreted by chondrocytes were measured in culture supernatant. In Phase II, retention capacity of externally added HA was quantified indirectly by measuring the HA released in culture supernatant, and in Phase III, the expression of CD44 on cells was analysed by immunohistochemistry.

RESULTS

In Phase I, the average HA in the 3D supernatant was 3% that of 2D. In phase II, 80% of externally added HA was detected in the 2D on day 7, while in 3D-TGP, only 0.1% was released until day 21. In Phase III, 2D yielded individual cells that started degenerating from the third week; in 3D-TGP cells grew for a longer duration, formed a tissue-like architecture with extracellular matrix with significantly intense staining of CD44 than 2D.

CONCLUSION

The capability of the 3D-TGP culture environment to retain HA and support chondrocytes to grow with a tissue-like architecture expressing higher HA content is considered advantageous as it serves as an in vitro culture platform that enables tissue engineering of cartilage tissue with native hyaline phenotype and higher HA expression. The in vitro environment being conducive, based on this data, we also recommend that the TGP be tried as an encapsulation material in clinical studies of chondrocyte implantation for optimal clinical outcome.

FGF2: a key regulator augmenting tendon-to-bone healing and cartilage repair

Ligament/tendon and cartilage injuries are clinically common diseases that perplex most clinicians. Because of the lack of blood vessels and nerves, their self-repairing abilities are rather poor. Therefore, surgeries are necessary and also widely used to treat ligament/tendon or cartilage injuries. However, after surgery, there are still many problems that affect healing. In recent years, it has been found that exogenous FGF2 plays an important role in the repair of ligament/tendon and cartilage injuries and exerts a synergistic effect with endogenous FGF2. Therefore, FGF2 can be used as a new type of biomolecule to accelerate tendon-to-bone healing and cartilage repair after injury.

The U3 and Env Proteins of Jaagsiekte Sheep Retrovirus and Enzootic Nasal Tumor Virus Both Contribute to Tissue Tropism

Jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus (ENTV) are small-ruminant betaretroviruses that share high nucleotide and amino acid identity, utilize the same cellular receptor, hyaluronoglucosaminidase 2 (Hyal2) for entry, and transform tissues with their envelope (Env) glycoprotein; yet, they target discrete regions of the respiratory tract—the lung and nose, respectively. This distinct tissue selectivity makes them ideal tools with which to study the pathogenesis of betaretroviruses. To uncover the genetic determinants of tropism, we constructed JSRV–ENTV chimeric viruses and produced lentivectors pseudotyped with the Env proteins from JSRV (Jenv) and ENTV (Eenv). Through the transduction and infection of lung and nasal turbinate tissue slices, we observed that Hyal2 expression levels strongly influence ENTV entry, but that the long terminal repeat (LTR) promoters of these viruses are likely responsible for tissue-specificity. Furthermore, we show evidence of ENTV Env expression in chondrocytes within ENTV-infected nasal turbinate tissue, where Hyal2 is highly expressed. Our work suggests that the unique tissue tropism of JSRV and ENTV stems from the combined effort of the envelope glycoprotein-receptor interactions and the LTR and provides new insight into the pathogenesis of ENTV.

Articular cartilage regeneration: The role of endogenous mesenchymal stem/progenitor cell recruitment and migration

BACKGROUND

Trauma- or osteoarthritis-related cartilage damage resulted in functional decline of joints and heavy burden of public health. Recently, the reparative role of mesenchymal stem/progenitor cells (MSCs) in articular cartilage (AC) reconstruction is drawing more and more attention.

OBJECTIVE

To provide a review on (1) the locations and categories of joint-resident MSCs, (2) the regulation of chondrogenic capacities of MSCs, (3) the migratory approaches of MSCs to diseased AC and regulatory mechanisms.

METHODS

PubMed and Web of Science were searched for English-language articles related to MSC recruitment and migration for AC repair until June 2019. The presence of various MSCs in or around joints, the potential approaches to diseased AC` and the regenerative capacities of MSCs were reviewed.

RESULTS

Various intra- and peri-articular MSCs, with inherent migratory potentials, are present in multiple stem cell niches in or around joints. The recruitment and migration of joint-resident MSCs play crucial roles in endogenous AC repair. Multiple recruiting signals, such as chemokines, growth factors, etc., emerge during the development of AC diseases and participate in the regulation of MSC mobilization. Motivated MSCs could migrate into cartilage lesions and then exert multiple reparative potentials, including extracellular matrix (ECM) reconstruction and microenvironment modulation.

CONCLUSION

In general, AC repair based on endogenous MSC recruitment and migration is a feasible strategy, and a promising research field. Furthermore, endogenous AC repair mediated by native MSCs would provide new opportunities to efficient preventative or therapeutic options for AC diseases.

Mesenchymal Stem Cells and Their Clinical Applications in Osteoarthritis

Osteoarthritis is a chronic degenerative joint disorder characterized by articular cartilage destruction and osteophyte formation. Chondrocytes in the matrix have a relatively slow turnover rate, and the tissue itself lacks a blood supply to support repair and remodeling. Researchers have evaluated the effectiveness of stem cell therapy and tissue engineering for treating osteoarthritis. All sources of stem cells, including embryonic, induced pluripotent, fetal, and adult stem cells, have potential use in stem cell therapy, which provides a permanent biological solution. Mesenchymal stem cells (MSCs) isolated from bone marrow, adipose tissue, and umbilical cord show considerable promise for use in cartilage repair. MSCs can be sourced from any or all joint tissues and can modulate the immune response. Additionally, MSCs can directly differentiate into chondrocytes under appropriate signal transduction. They also have immunosuppressive and anti-inflammatory paracrine effects. This article reviews the current clinical applications of MSCs and future directions of research in osteoarthritis.