The healing of the tendon-bone interface is a complex dynamic process involving the interaction of multiple cellular and molecular signaling pathways. Bone mesenchymal stem cells (BMSCs) have the potential to differentiate into various types of cells, including osteoblasts, chondrocytes and adipocytes, etc., and have the potential to regenerate damaged tissues. They are potential seed cells for promoting tendon-bone healing. How to precisely regulate the proliferation and differentiation of BMSCs to accelerate the process of tendon-bone healing is a current research hotspot. Monomers of traditional Chinese medicine can promote tendon-bone healing by regulating signaling pathways such as Wnt/β-catenin and BMP/Smad to induce osteogenic and chondrogenic differentiation of BMSCs. This article reviews from several aspects such as the regulatory role of related signaling pathways on tendine-bone healing, traditional Chinese medicine monomers and their mechanism of regulating BMSCs to promote tendine-bone healing in order to providing new ideas for promoting tendine-bone healing.
Mesenchymal Stem Cells/cytology* ; Humans ; Animals ; Bone Marrow Cells/cytology* ; Bone and Bones/drug effects* ; Wound Healing/drug effects* ; Medicine, Chinese Traditional ; Tendons/drug effects* ; Drugs, Chinese Herbal/pharmacology* ; Signal Transduction/drug effects* ; Cell Differentiation/drug effects*

OBJECTIVETo explore function and related molecular mechanism of osteopractic total flavone (OTF) on tendon healing in rats.

METHODSTen male rats aged for 8 weeks were collected and weighted from 180 to 220 g. Tendon stem cells were cultivated, the third tendon stem cells were used for experiment. OTP treated with 0, 0.1, 1, 10 ng/ml were added into tendon stem cells, and expression change of ALP, Runx2, OCN, VEGF, P-S6, P-4E/BP1 were detected after 14 days. Forty male rats aged for 8 weeks (weighted 180 to 220 g) were established extra-articular tendon-bone transplanting healing model, and divided into experimental group and control group. Experimental group were treated with OTF(100 mg·kg⁻¹·d⁻¹), while control group was treated by normal saline with the same volume. Tendon-bone healing degree were detected by biomechanical testing at 3 and 6 weeks after surgery, histological detection were applied to detect tendon-bone healing and number of new vessles.

RESULTSAfter treated by OTP, ALP staining and active index detection showed there were statistical differences among 0, 0.1, 1, 10 ng/ml group. After 14 days' cultivation, western blotting results showed mTOR downstream marker protein P-S6 protein expression were gradually increased with increase of density of OTP, expression of P-4E/BP1 was reduced, while expression of Runx2, OCN, VEGF were increased. Biological detection results showed that there was no significant difference in mechanical strength between experimental group(0.78±0.05) N/mm and control group (0.51±0.02) N/mm at 3 weeks after surgery, while mechanical strength in experimental group (1.36±0.09) N/mm was higher than control group (1.01±0.08) N/mm at 6 weeks after surgery. Histological results showed maturity of tendon-bone surface cell were higher at 3 and 6 weeks in experimental group, sharpey fiber growth more density, calcification extent of mesenchyme was high, and new bone, vessels were increased.

CONCLUSIONSOTF could promote osteogenic differentiation of tendon stem cells through mTOR signaling in vitro, and stimulate tendon-bone healing in bone tunnel and enhance connection quality between tendon and bone.

Animals ; Biomechanical Phenomena ; Bone Transplantation ; Cell Differentiation ; Cells, Cultured ; Flavones ; pharmacology ; Male ; Osteogenesis ; Rats ; Stem Cells ; cytology ; TOR Serine-Threonine Kinases ; metabolism ; Tendons ; cytology ; transplantation ; Wound Healing

OBJECTIVETo investigate the effects of three-dimensional parallel collagen scaffold on the cell shape, arrangement and extracellular matrix formation of tendon stem cells.

METHODSParallel collagen scaffold was fabricated by unidirectional freezing technique, while random collagen scaffold was fabricated by freeze-drying technique. The effects of two scaffolds on cell shape and extracellular matrix formation were investigated in vitro by seeding tendon stem/progenitor cells and in vivo by ectopic implantation.

RESULTSParallel and random collagen scaffolds were produced successfully. Parallel collagen scaffold was more akin to tendon than random collagen scaffold. Tendon stem/progenitor cells were spindle-shaped and unified orientated in parallel collagen scaffold, while cells on random collagen scaffold had disorder orientation. Two weeks after ectopic implantation, cells had nearly the same orientation with the collagen substance. In parallel collagen scaffold, cells had parallel arrangement, and more spindly cells were observed. By contrast, cells in random collagen scaffold were disorder.

CONCLUSIONParallel collagen scaffold can induce cells to be in spindly and parallel arrangement, and promote parallel extracellular matrix formation; while random collagen scaffold can induce cells in random arrangement. The results indicate that parallel collagen scaffold is an ideal structure to promote tendon repairing.

Collagen ; chemistry ; Extracellular Matrix ; physiology ; Freeze Drying ; Freezing ; Humans ; Stem Cells ; cytology ; Tendons ; cytology ; growth & development ; Tissue Engineering ; Tissue Scaffolds ; chemistry

OBJECTIVETo evaluate the application of tendon-derived stem cells (TDSC) and bone marrow-derived mesenchymal stem cells (BMSC) for patellar tendon injury repair in rat model.

METHODSTDSCs and BMSCs were isolated from patellar tendons or bone marrow of healthy SD rats. The patellar tendon injury model was induced in 60 SD rats, then the animals were divided into 3 groups with 20 in each group: rats in TDSC group received transplantation of TDSC with fibrin glue in defected patellar tendon, rats in BMSC group received BMSC with fibrin glue for transplantation and those in control group received fibrin glue only. The gross morphology, histology and biomechanics of the patellar tendon were examined at 1, 2, 4, 6 and 8 weeks after the treatment.

RESULTSGross observation showed that the tendon defects in TDSC group and BMSC group almost disappeared in week 8, while the boundary of tendon defects in control group was still visible. Histology examination showed that the neo-tendon formation in TDSC group and BMSC group was observed at week 8, while there was no neo-tendon formation in control group. Biomechanics study showed that the ultimate stress and Young Modulus, relative ultimate stress and relative Young Modulus increased with the time going in all groups(all P<0.05); the ultimate stress and Young Modulus, relative ultimate stress and relative Young Modulus of TDSC and BMSC groups were significantly higher than those in control group at week 4, 6 and 8(all P<0.05). There was no difference in ultimate stress and Young Modulus between TDSC group and BMSC group(P>0.05), however, the relative Young Modulus of TDSC group was significantly higher than that in BMSC group at week 8(P<0.05).

CONCLUSIONAllogeneic TDSC and BMSC transplantation facilitates the repair of tendon injury and improves the biomechanics of tendon. TDSC is more suitable for in vivo tendon regeneration than BMSC.

Animals ; Bone Marrow ; Elastic Modulus ; Mesenchymal Stromal Cells ; cytology ; Rats ; Rats, Sprague-Dawley ; Regeneration ; Tendon Injuries ; therapy ; Tendons ; cytology ; Wound Healing

Embryonic stem cells have unlimited proliferative capacity, which may provide a source of tendon stem/progenitor cells for tissue engineering. Experts of International Science and Technology Collaborative Program of Ministry of Science and Technology have developed a protocol consensus on differentiation of human embryonic stem cells into the tendon cells. The consensus recommends a protocol of two-step generation of human embryonic stem cells into tendon cells: the human embryonic stem cells are first differentiated into mesenchymal stem cells on different material surfaces; then with the scaffold-free tissue engineering tendon formed by high-density planting, the mesenchymal stem cells are induced into tendon cells under static or dynamic mechanical stimulation in vivo and in vitro. Tissue engineering tendon established in vitro by the protocol can be used as a model in toxicological analysis and safety evaluation of tendon-relevant small molecule compounds, medical materials and drugs.
Cell Differentiation ; Consensus ; Human Embryonic Stem Cells ; cytology ; Humans ; Mesenchymal Stromal Cells ; cytology ; Tendons ; cytology ; Tissue Engineering

OBJECTIVETo investigate a method that constructing a tissue-engineered tendon with a continuous and heterogeneous transition region.

METHODSFibroblasts derived from rabbit epithelial tissue were cultured in vitro and collagen gel was prepared. The experimental groups were scaffold only group, fibroblasts+ chondrocytes group (Fb+ CC group), fibroblasts+ osteoblasts group (Fb+ OB group), fibroblasts+ chondrocytes+ osteoblasts group (Fb+ CC+ OB group). Heterogeneous cell populations(fibroblasts, chondrocytes and osteoblasts) with collagen gel were seeded within three predesigned specific regions (fibrogenesis, chondrogenesis, and osteogenesis) of decellularized rabbit achilles tendons to fabricate a stratified scaffold containing three biofunctional regions supporting fibrogenesis, chondrogenesis, and osteogenesis. The tests of morphology, architecture and cytocompatibility of the scaffolds were performed. Gradient tissue-specific matrix formation was analysed within the predesignated regions via histological staining and immunofluorescence assays.

RESULTSThe HE staining and scanning electron microscopy analysis demonstrated that no major cell fragments or nuclear material was evident, and increased intra-fascicular and inter-fascicular spaces were found, the cytocompatibility of the scaffolds showed that the numbers of viable cells on the scaffold surfaces increase steadily, no significant differences were found between the scaffold only containing ordinary culture medium and scaffold containing gel groups. Histological staining and immunofluorescence assays demonstrated that the cartilage-related markers (GAG, COL2A1) were found only in the chondrogenesis region, but bone-related proteins only in the osteogenesis region of bone tunnel, and fibrosis was remarkable for the fibrogenesis region in the joint cavity. The transitional architecture with ligament-fibrocartilage-bone was constructed in the ligament-bone tunnel interface.

CONCLUSIONSA transitional interface (fiber-fiberocartilage-bone) could be replicated in a decellularized tendon through stratified tissue integration in vitro. The cell-tendon complex offers the advantages of a multi-tissue transition involving controlled cellular interactions and matrix heterogeneity.

Animals ; Bone and Bones ; Cells, Cultured ; Chondrocytes ; cytology ; Collagen ; Fibroblasts ; cytology ; Ligaments ; Osteoblasts ; cytology ; Rabbits ; Tendons ; Tissue Engineering ; methods

Tendon tissue engineering is a novel therapeutic strategy for severe tendon injury and loss. Adipose derived stem cells (ASCs) have been studied extensively, due to their potency to differentiate into musculoskeletal tissue precursors such as osteoblasts, chondrocytes, adipocytes, and tendocytes under specific cues and high ability of proliferation. Resources of ASCs are ubiquitous and isolation of ASCs is secure, simple and minimally invasive. Mounting evidences demonstrate that ASCs may be involved in tendon tissue engineering and repair the severe injury of tendon under stimulation of various growth factors and other appropriate fittings.
Adipocytes ; Adipose Tissue ; cytology ; Cell Differentiation ; Chondrocytes ; Humans ; Osteoblasts ; Stem Cells ; cytology ; Tendon Injuries ; therapy ; Tendons ; cytology ; Tissue Engineering ; Wound Healing

BACKGROUNDRecent studies showed that bone marrow-derived mesenchymal stem cells (BMSCs) had risk of ectopic bone formation. In this study, we aimed to investigate the effect of growth and differentiation factor 6 (GDF-6) on the tenogenic differentiation of BMSCs in vitro, and then combined with small intestine submucous (SIS) to promote tendon regeneration in vivo.

METHODSThe BMSCs were isolated from the green fluorescent protein (GFP) rats, and were characterized by multi-differentiation assays following our previous study protocol. BMSCs cultured with different concentrations of GDF-6, without growth factors served as control. After 2 weeks, mRNA expression and protein expression of tendon specific markers were examined by qRT-PCR and Western blotting to define an optimal concentration of GDF-6. Mann-Whitney U-test was used to compare the difference in relative mRNA expression among all groups; P ≤ 0.05 was regarded as statistically significant. The GDF-6 treated BMSCs combined with SIS were implanted in nude mice and SD rat acute patellar tendon injury model, the BMSCs combined with SIS served as control. After 12 and 4 weeks in nude mice and tendon injury model, the samples were collected for histology.

RESULTSAfter the BMSCs were treated with different concentration of GDF-6 for 2 weeks, the fold changes of the specific markers (Tenomodulin and Scleraxis) mRNA expression were significantly higher in GDF-6 (20 ng/ml) group (P ≤ 0.05), which was also confirmed by Western blotting result. The BMSCs became parallel in orientation after GDF-6 (20 ng/ml) treatment, but the BMSCs in control group were randomly oriented. The GDF-6 (20 ng/ml) treated BMSCs were combined with SIS, and were implanted in nude mice for 12 weeks, the histology showed neo-tendon formation. In the SD rat patellar tendon window injury model, the histology also indicated the GDF-6 (20 ng/ml) treated BMSCs combined with SIS could promote tendon regeneration.

CONCLUSIONSGDF-6 has tenogenic effect on the tenogenic differentiation of BMSCs, and GDF-6 (20 ng/ml) has better tenogenic effect compared to other concentrations. The GDF-6 (20 ng/ml) treated BMSCs combined with SIS can form neo-tendons and promote tendon regeneration.

Animals ; Cell Differentiation ; drug effects ; Growth Differentiation Factor 6 ; pharmacology ; Male ; Membrane Proteins ; genetics ; Mesenchymal Stromal Cells ; cytology ; drug effects ; Mice ; Mice, Nude ; Rats ; Rats, Sprague-Dawley ; Regeneration ; drug effects ; Tendons ; drug effects ; physiology

OBJECTIVETo optimize the culture media by adding the growth factors required to maintain tenocytes survival and promote their differentiation without fetal bovine serum (FBS) supplementation, in order for the approach to be used for any future tendon tissue engineering.

METHODSThe human tenocytes were cultured in α-MEM media by adding FBS at various concentrations and supplementing both insulin-like growth factor 1 (IGF-1) and transforming growth factor β-3 (TGFβ-3). A number of growth factors were selected that could support tenocytes expansion at reduced differentiated state with the minimum FBS. By employing fractional factorial design, different treatment groups went through AlamarBlue(TM) tests to evaluate the cell number growth whilst collagen quantification by real time RT-PCR technique and tenocyte differentiation were also studied.

RESULTSThe tenocytes cultured for 14 days with 0% FBS, 50 ng/ml IGF-1 and 10 ng/ml TGFβ-3 maintained survival over 14 days, the Cell count were 6228.68 ± 43.87. They were higher than the other experimental groups, but less than 10% FBS control group (13 576.74 ± 286.75, t = 41.29, P < 0.05). The tenocytes cultured in the treated group also showed enhanced collagen synthesis ((0.322 ± 0.003) ng, t = 4.13 - 5.93, P < 0.05).

CONCLUSIONThese findings have shown for the first time that human tenocytes could be maintained survival for a long period of time in the culture media without FBS, having this approach a suitable one for tendon tissue engineering.

Cell Differentiation ; drug effects ; Cell Survival ; drug effects ; Cells, Cultured ; Collagen ; biosynthesis ; Culture Media ; pharmacology ; Humans ; Insulin-Like Growth Factor I ; pharmacology ; Tendons ; cytology ; drug effects ; metabolism ; Transforming Growth Factor beta3 ; pharmacology

By observations of the features of ultrastructure changes in the tissue engineered artificial tendon of vitreous cryopreservation, we investigated the repairing effect of tendon after an in-vivo implantation and hence we provided an important theoretical and experimental basis for the vitreous cryopreservation and application of tissue engineered artificial tendon. After vitreous cryopreservation, the implantation materials of tissue engineered artificial tendon dynamically constructed in vitro were implanted in rats for reparation of the tendon defect. A scanning electron microscope was used. At the 2nd week, the materials presented a reticular formation and there were juvenile tendon cells among materials. At the 6th week, materials were already degraded and absorbed, and then were substituted by neonatal tendon cells and collagen fibers. At the 8th week, dense tendon tissues containing uniform tendon cells and collagen fibers were found already formed; the density of collagen fibers significantly increased with time. Using a transmission electron microscope at the 2nd week, we found active proliferation of tendon cells; most of them were immature cells with a complete nuclear membrane, clear nucleolus and little collagen fibers. At the 6th week, tendon cells were more mature with a little-sized, deep-stained nucleolus surrounded by plenty of collagen fibers with complete fiber structure and clear cross striation. There was no significant difference between the two groups. Using an electron microscope, we found a very good agreement in observation of the tissue engineered artificial tendon after the in-vivo implantation in two groups. Neonatal tendon cells and collagen fiber tissues grew well and are in a similar form and order when compared versus normal tendon tissues. This proved that vitreous cryopreservation has no significant influence on the function of tendon cells. The neonatal tissue-engineered tendon exerts good function of growth and repair.
Achilles Tendon ; injuries ; surgery ; ultrastructure ; Animals ; Cryopreservation ; Female ; Male ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Tendons ; cytology ; transplantation ; Tissue Engineering ; methods ; Tissue Preservation ; methods ; Tissue Scaffolds ; Vitrification