Combined effect of ligament stem cells and umbilical-cord-blood-derived CD34+ cells on ligament healing

Mesenchymal Stem Cells for Enhanced Healing of the Medial Collateral Ligament of the Knee Joint

Background and Objectives: The medial collateral ligament (MCL) is one of the major supporting ligaments of the knee joint, and MCL injuries are common where excessive valgus loading is applied to the knee joint. Although most MCL injuries can be treated conservatively, healing of the MCL can take several weeks to months. Furthermore, once injured, the biomechanical properties of the healed MCL differ from those of the native MCL, resulting in an increased risk of re-injury and chronic remnant symptoms. Mesenchymal stem cells (MSCs), owing to their therapeutic potential, have been investigated in various musculoskeletal injuries, and some preclinical studies regarding MSC-based approaches in MCL injuries have shown promising results. Despite satisfactory results in preclinical studies, there is still a lack of clinical studies in the orthopedic literature. This article describes the basic knowledge of the MCL, standard treatments for MCL injuries, and recent studies regarding the application of MSCs for enhanced healing of the MCL. MSC-based approaches are expected to be a potential therapeutic option for enhanced healing of the MCL in the future.

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

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

IVD progenitor cells: a new horizon for understanding disc homeostasis and repair

Intervertebral disc (IVD) degeneration is associated with low back pain. In IVDs, a high mechanical load, high osmotic pressure and hypoxic conditions create a hostile microenvironment for resident cells. How IVD homeostasis and function are maintained under stress remains to be understood; however, several research groups have reported isolating native endogenous progenitor-like or otherwise proliferative cells from the IVD. The isolation of such cells implies that the IVD might contain a quiescent progenitor-like population that could be activated for IVD repair and regeneration. Increased understanding of endogenous disc progenitor cells will improve our knowledge of IVD homeostasis and, when combined with tissue engineering techniques, might hold promise for future therapeutic applications. In this Review, the characteristics of progenitor cells in different IVD compartments are discussed, as well as the potency of different cell populations within the IVD. The stem cell characteristics of these cells are also compared with those of mesenchymal stromal cells. On the basis of existing evidence, whether and how IVD degeneration and the hostile microenvironment might affect endogenous progenitor cell function are considered, and ways to channel the potential of these cells for IVD repair are suggested.

Tendon and Ligament Healing and Current Approaches to Tendon and Ligament Regeneration

Ligament and tendon injuries are common problems in orthopedics. There is a need for treatments that can expedite nonoperative healing or improve the efficacy of surgical repair or reconstruction of ligaments and tendons. Successful biologically-based attempts at repair and reconstruction would require a thorough understanding of normal tendon and ligament healing. The inflammatory, proliferative, and remodeling phases, and the cells involved in tendon and ligament healing will be reviewed. Then, current research efforts focusing on biologically-based treatments of ligament and tendon injuries will be summarized, with a focus on stem cells endogenous to tendons and ligaments. Statement of clinical significance: This paper details mechanisms of ligament and tendon healing, as well as attempts to apply stem cells to ligament and tendon healing. Understanding of these topics could lead to more efficacious therapies to treat ligament and tendon injuries. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:7-12, 2020.

Critical assessment of the efficiency of CD34 and CD133 antibodies for enrichment of rabbit hematopoietic stem cells

Rabbits have many hereditary diseases common to humans and are therefore a valuable model for regenerative disease and hematopoietic stem cell (HSC) therapies. Currently, there is no substantial data on the isolation and/or enrichment of rabbit HSCs. This study was initiated to evaluate the efficiency of the commercially available anti-CD34 and anti-CD133 antibodies for the detection and potential enrichment of rabbit HSCs from peripheral blood. PBMCs from rabbit and human blood were labelled with different clones of anti-human CD34 monoclonal antibodies (AC136, 581, and 8G12) and rabbit polyclonal CD34 antibody (pCD34) and anti-human CD133 monoclonal antibodies (AC133 and 293C3). Flow cytometry showed a higher percentage of rabbit CD34⁺ cells labelled by AC136 in comparison to the clone 581 and pCD34 (P < 0.01). A higher percentage of rabbit CD133⁺ cells were also detected by 293C3 compared to the AC133 clone (P < 0.01). Therefore, AC136 clone was used for the indirect immunomagnetic enrichment of rabbit CD34⁺ cells using magnetic-activated cell sorting (MACS). The enrichment of the rabbit CD34⁺ cells after sorting was low in comparison to human samples (2.4% vs. 39.6%). PCR analyses confirmed the efficient enrichment of human CD34⁺ cells and the low expression of CD34 mRNA in rabbit positive fraction. In conclusion, the tested antibodies might be suitable for detection, but not for sorting the rabbit CD34⁺ HSCs and new specific anti-rabbit CD34 antibodies are needed for efficient enrichment of rabbit HSCs. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018 © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1278-1289, 2018.

The Use of Endothelial Progenitor Cells for the Regeneration of Musculoskeletal and Neural Tissues

Endothelial progenitor cells (EPCs) derived from bone marrow and blood can differentiate into endothelial cells and promote neovascularization. In addition, EPCs are a promising cell source for the repair of various types of vascularized tissues and have been used in animal experiments and clinical trials for tissue repair. In this review, we focused on the kinetics of endogenous EPCs during tissue repair and the application of EPCs or stem cell populations containing EPCs for tissue regeneration in musculoskeletal and neural tissues including the bone, skeletal muscle, ligaments, spinal cord, and peripheral nerves. EPCs can be mobilized from bone marrow and recruited to injured tissue to contribute to neovascularization and tissue repair. In addition, EPCs or stem cell populations containing EPCs promote neovascularization and tissue repair through their differentiation to endothelial cells or tissue-specific cells, the upregulation of growth factors, and the induction and activation of endogenous stem cells. Human peripheral blood CD34(+) cells containing EPCs have been used in clinical trials of bone repair. Thus, EPCs are a promising cell source for the treatment of musculoskeletal and neural tissue injury.

Ligament-Derived Stem Cells: Identification, Characterisation, and Therapeutic Application

Ligament is prone to injury and degeneration and has poor healing potential and, with currently ineffective treatment strategies, stem cell therapies may provide an exciting new treatment option. Ligament-derived stem cell (LDSC) populations have been isolated from a number of different ligament types with the majority of studies focussing on periodontal ligament. To date, only a few studies have investigated LDSC populations in other types of ligament, for example, intra-articular ligaments; however, this now appears to be a developing field. This literature review aims to summarise the current information on nondental LDSCs including in vitro characteristics of LDSCs and their therapeutic potential. The stem cell niche has been shown to be vital for stem cell survival and function in a number of different physiological systems; therefore, the LDSC niche may have an impact on LDSC phenotype. The role of the LDSC niche on LDSC viability and function will be discussed as well as the therapeutic potential of LDSC niche modulation.