Haoye Meng

Basic science and clinical application of platelet-rich plasma for cartilage defects and osteoarthritis: a review

Cartilage defects (CDs) and the most common joint disease, osteoarthritis (OA), are characterized by degeneration of the articular cartilage that ultimately leads to joint destruction. Current treatment strategies are inadequate: none results in restoration of fully functional hyaline cartilage, for uncertain long-term prognosis. Tissue engineering of cartilage with auto-cartilage cells or appropriate mesenchymal stem cell (MSC)-derived cartilage cells is currently being investigated to search for new therapies. Platelet-rich plasma (PRP), an autologous source of factors obtained by centrifugation, possesses various functions. For culture of MSCs and cartilage cells, it might be substituted for fetal bovine serum (FBS) with high efficiency and safety. It enhances the regeneration of cartilage cells when added to cartilage tissue engineering constructs for repairing CDs and as regenerative injection therapy for OA. But challenges also remain. Some of the growth factors (GFs) present in PRP have negative effects on the OA joint. It is therefore unlikely that a mix of GFs some of which have negative effects in the OA joint, as present in PRP, will be of benefit in OA. Future directions of PRP application may concentrate on seeking an appropriate and innocuous agent like anti-VEGF antibody that can modulate and control the effect of PRP.

A novel long non-coding RNA, hypoxia-inducible factor-2α promoter upstream transcript, functions as an inhibitor of osteosarcoma stem cells in vitro

Long non-coding RNAs (lncRNAs) have recently been identified as novel modulators of malignant tumors. However, the function of lncRNAs in cancer stem cells (CSCs) remains to be elucidated. The present study aimed to investigate the regulating role of a novel lncRNA, hypoxia-inducible factor-2α (HIF-2α) promoter upstream transcript (HIF2PUT), in osteosarcoma stem cells. The expression levels of HIF2PUT were assessed by quantitative polymerase chain reaction in 17 osteosarcoma tissue specimens, and the correlation between the expression of HIF2PUT and its host transcript-HIF-2α was determined. In functional experiments, HIF2PUT expression was knocked down by small interfering RNAs, or overexpressed by transfection with pcDNA-HIF2PUT, in order to evaluate the effects of HIF2PUT on cell proliferation, migration, expression rate of osteosarcoma stem cell marker CD133, and stem sphere-forming ability in MG63 cells. HIF2PUT expression levels were positively correlated with HIF-2α in osteosarcoma tissues. Overexpression of HIF2PUT markedly inhibited cell proliferation and migration, decreased the percentage of CD133 expressing cells, and impaired the osteosarcoma stem sphere-forming ability of the MG63 cells. Whereas, knockdown of HIF2PUT expression had the opposite effect. Furthermore, altering the expression of HIF2PUT resulted in a concomitant change to HIF-2α mRNA expression. These results indicate that the lncRNA HIF2PUT may be a novel regulatory factor of osteosarcoma stem cells, which may exert its function partly by controlling HIF-2α expression. Further studies regarding HIF2PUT may provide a novel therapeutic target of osteosarcoma in the future.

Differentiation of Bone Marrow Mesenchymal Stem Cells in Osteoblasts and Adipocytes and its Role in Treatment of Osteoporosis

Osteoporosis is a systemic metabolic bone disorder characterized by a decrease in bone mass and degradation of the bone microstructure, leaving bones that are fragile and prone to fracture. Most osteoporosis treatments improve symptoms, but to date there is no quick and effective therapy. Bone marrow mesenchymal stem cells (BMMSCs) have pluripotent potential. In adults, BMMSCs differentiate mainly into osteoblasts and adipocytes in the skeleton. However, if this differentiation is unbalanced, it may lead to a decrease in bone mass. If the number of adipocyte cells increases and that of osteoblast cells decreases, osteoporosis can result. A variety of hormones and cytokines play an important role in the regulation of BMMSCs bidirectional differentiation. Therefore, a greater understanding of the regulation mechanism of BMMSC differentiation may provide new methods to prevent and treat osteoporosis. In addition, autologous, allogeneic BMMSCs or genetically modified BMMSC transplantation can effectively increase bone mass and density, increase bone mechanical strength, correct the imbalance in bone metabolism, and increase bone formation, and is expected to provide a new strategy and method for the treatment of osteoporosis.

Induction of mesenchymal stem cell chondrogenic differentiation and functional cartilage microtissue formation for in vivo cartilage regeneration by cartilage extracellular matrix-derived particles.

UNLABELLED We propose a method of preparing a novel cell carrier derived from natural cartilage extracellular matrix (ECM), designated cartilage ECM-derived particles (CEDPs). Through a series of processes involving pulverization, sieving, and decellularization, fresh cartilage was made into CEDPs with a median diameter of 263 ± 48 μm. Under microgravity culture conditions in a rotary cell culture system (RCCS), bone marrow stromal cells (BMSCs) can proliferate rapidly on the surface of CEDPs with high viability. Histological evaluation and gene expression analysis indicated that BMSCs were differentiated into mature chondrocytes after 21 days of culture without the use of exogenous growth factors. Functional cartilage microtissue aggregates of BMSC-laden CEDPs formed as time in culture increased. Further, the microtissue aggregates were directly implanted into trochlear cartilage defects in a rat model (CEDP+MSC group). Gait analysis and histological results indicated that the CEDP+MSC group obtained better and more rapid joint function recovery and superior cartilage repair compared to the control groups, in which defects were treated with CEDPs alone or only fibrin glue, at both 6 and 12 weeks after surgery. In conclusion, the innovative cell carrier derived from cartilage ECM could promote chondrogenic differentiation of BMSCs, and the direct use of functional cartilage microtissue facilitated cartilage regeneration. This strategy for cell culture, stem cell differentiation and one-step surgery using cartilage microtissue for cartilage repair provides novel prospects for cartilage tissue engineering and may have further broad clinical applications. STATEMENT OF SIGNIFICANCE We proposed a method to prepare a novel cell carrier derived from natural cartilage ECM, termed cartilage ECM-derived particles (CEDPs), which can support proliferation of MSCs and facilitate their chondrogenic differentiation. Further, the direct use of functional cartilage microtissue of MSC-laden CEDP aggregates for cartilage repair in vivo induced hyaline-like articular cartilage repair. This strategy for cell culture, stem cell differentiation and the one-step surgery for cartilage repair provide novel prospects for cartilage tissue engineering and may have further broad clinical applications.

MicroRNAs' Involvement in Osteoarthritis and the Prospects for Treatments

Osteoarthritis (OA) is a chronic disease and its etiology is complex. With increasing OA incidence, more and more people are facing heavy financial and social burdens from the disease. Genetics-related aspects of OA pathogenesis are not well understood. Recent reports have examined the molecular mechanisms and genes related to OA. It has been realized that genetic changes in articular cartilage and bone may contribute to OAs development. Osteoclasts, osteoblasts, osteocytes, and chondrocytes in joints must express appropriate genes to achieve tissue homeostasis, and errors in this can cause OA. MicroRNAs (miRNAs) are small noncoding RNAs that have been discovered to be overarching regulators of gene expression. Their ability to repress many target genes and their target-binding specificity indicate a complex network of interactions, which is still being defined. Many studies have focused on the role of miRNAs in bone and cartilage and have identified numbers of miRNAs that play important roles in regulating bone and cartilage homeostasis. Those miRNAs may also be involved in the pathology of OA, which is the focus of this review. Future studies on the role of miRNAs in OA will provide important clues leading to a better understanding of the mechanism(s) of OA and, more particularly, to the development of therapeutic targets for OA.

Immobilization of collagen peptide on dialdehyde bacterial cellulose nanofibers via covalent bonds for tissue engineering and regeneration

Bacterial cellulose (BC) is an alternative nanostructured biomaterial to be utilized for a wide range of biomedical applications. Because of its low bioactivity, which restricted its practical application, collagen and collagen hydrolysate were usually composited into BC. It is necessary to develop a new method to generate covalent bonds between collagen and cellulose to improve the immobilization of collagen on BC. This study describes a facile dialdehyde BC/collagen peptide nanocomposite. BC was oxidized into dialdehyde bacterial cellulose (DBC) by regioselective oxidation, and then composited with collagen peptide (Col-p) via covalent bonds to form Schiff’s base type compounds, which was demonstrated by the results of microstructures, contact angle, Col-p content, and peptide-binding ratio. The peptide-binding ratio was further affected by the degree of oxidation, pH value, and zeta potential. In vitro desorption measurement of Col-p suggested a controlled release mechanism of the nanocomposite. Cell tests indicated that the prepared DBC/Col-p composite was bioactive and suitable for cell adhesion and attachment. This work demonstrates that the DBC/Col-p composite is a promising material for tissue engineering and regeneration.

Extracellular matrix from human umbilical cord-derived mesenchymal stem cells as a scaffold for peripheral nerve regeneration

The extracellular matrix, which includes collagens, laminin, or fibronectin, plays an important role in peripheral nerve regeneration. Recently, a Schwann cell-derived extracellular matrix with classical biomaterial was used to mimic the neural niche. However, extensive clinical use of Schwann cells remains limited because of the limited origin, loss of an autologous nerve, and extended in vitro culture times. In the present study, human umbilical cord-derived mesenchymal stem cells (hUCMSCs), which are easily accessible and more proliferative than Schwann cells, were used to prepare an extracellular matrix. We identified the morphology and function of hUCMSCs and investigated their effect on peripheral nerve regeneration. Compared with a non-coated dish tissue culture, the hUCMSC-derived extracellular matrix enhanced Schwann cell proliferation, upregulated gene and protein expression levels of brain-derived neurotrophic factor, glial cell-derived neurotrophic factor, and vascular endothelial growth factor in Schwann cells, and enhanced neurite outgrowth from dorsal root ganglion neurons. These findings suggest that the hUCMSC-derived extracellular matrix promotes peripheral nerve repair and can be used as a basis for the rational design of engineered neural niches.

Effect of Cervus and Cucumis Peptides on Osteoblast Activity and Fracture Healing in Osteoporotic Bone

Osteoporosis is associated with delayed and/or reduced fracture healing. As cervus and cucumis are the traditional Chinese treatments for rheumatoid arthritis, we investigated the effect of supplementation of these peptides (CCP) on bone fracture healing in ovariectomized (OVX) osteoporotic rats in vitro and in vivo. CCP enhanced osteoblast proliferation and increased alkaline phosphatase activity, matrix mineralization, and expression of runt-related transcription factor 2 (Runx2), bone morphogenetic protein 4 (BMP4), and osteopontin. In vivo, female Sprague-Dawley rats underwent ovariectomy and the right femora were fractured and fixed by intramedullary nailing 3 months later. Rats received intraperitoneal injections of either CCP (1.67 mg/kg) or physiological saline every day for 30 days. Fracture healing and callus formation were evaluated by radiography, micro-CT, biomechanical testing, and histology. At 12 weeks after fracture, calluses in CCP-treated bones showed significantly higher torsional strength and greater stiffness than control-treated bones. Bones in CCP-treated rats reunified and were thoroughly remodeled, while two saline-treated rats showed no bone union and incomplete remodeling. Taken together, these results indicate that use of CCP after fracture in osteoporotic rats accelerates mineralization and osteogenesis and improves fracture healing.

Research progress regarding nanohydroxyapatite and its composite biomaterials in bone defect repair

ABSTRACT Bone defects are very common, and there has been a great deal of research in the field of orthopedics to find ideal materials to repair such defects. Nanohydroxyapatite is a good bone substitute material; it has a number of structural similarities to natural bone, can promote new bone formation, is noncytotoxic, and has good biodegradability and biocompatibility. The use of composite and polymeric biomaterials can overcome the problems associated with the brittleness and weak mechanical properties of nanohydroxyapatite. Nanohydroxyapatite and its composite biomaterials were confirmed to play important roles in bone defect repair. This review presents a comparison of research regarding use of nanohydroxyapatite and its composite biomaterials in repairing bone defects. The goal is to identify the artificial bone substitute materials with the best biocompatibility and clinical repairing effects for various individuals and clinical situations. GRAPHICAL ABSTRACT

The optimal time to inject bone mesenchymal stem cells for fracture healing in a murine model

BackgroundBone marrow is an important source of stem cells, which can promote bone fracture healing.MethodsWe investigated the optimal time to inject bone marrow mesenchymal stem cells (BMSCs) in a C57 murine unilateral, transverse, femur fracture model. BMSCs transfected with red fluorescent protein (RFP-BMSCs) were injected via the tail vein on day 1, 7, or 14 post-fracture. AMD3100 (inhibitor of stromal cell-derived factor 1 [SDF-1]) was also injected before RFP-BMSCs in one group for comparison; a control group received saline injections. RFP-BMSC migration and fracture healing were evaluated by in vivo fluorescence assay. Micro-CT was performed and mechanical testing and histological analysis. Chemokine levels were evaluated by quantitative real-time PCR and western blotting.ResultsFollowing injection on day 7 post-fracture, RFP-BMSCs more frequently homed to the fracture site and remained for a longer duration. Bone volume and bone mineral density were increased when BMSCs were injected on day 7 post-fracture (P < 0.05). The mechanical properties of fractured femurs were improved following day-7 BMSC injection. Histology confirmed that BMSC injection improved the formation of new bones.ConclusionsChemokines that induce BMSC migration were highly expressed, and protein levels of osteogenesis-related factors were increased. Seven days after fracture may be the optimal time for injection of BMSCs to promote fracture healing. Additionally, the SDF-1/CXCR4 pathway may play an important role in fracture healing following BMSC injection.