Bo Bai

The present study introduced a direct co‐culture of mouse ATDC5 cells and primary porcine chondrocytes into a microcavitary hydrogel, which possessed advantages in promoting the growth of chondrocytes and retaining the phenotype. These two types of cells were encapsulated with gelatin microspheres in alginate hydrogels in either of the three ratios (3:1, 1:1, or 1:3 of ATDC5 cells to chondrocytes) and cultured in chondrogenic medium for 28 days. Simultaneously, the single encapsulation of ATDC5 cells or chondrocytes was set as a control. Cell Counting Kit‐8 (CCK‐8), real‐time PCR, and immunohistochemistry staining were used to evaluate the effect of various ratios of co‐cultured ATDC5 cells and chondrocytes on the expression of the cartilaginous phenotype. The CCK‐8 data indicated that the ratio of 3:1 group had an outstanding ability of cell growth. The other results demonstrated that higher the ATDC5 ratios and longer the culture duration, greater the expression of cartilage‐specific genes (including type II collagen and aggrecan) and more the synthesized cartilaginous extracellular matrix. Also, the Western blot analysis suggested that p44/42 MAP Kinase was involved in cell proliferation. However, due to the direct co‐culture of the two cell types, the underlying mechanism necessitates further investigation. Overall, the co‐culture system in microcavitary hydrogel improved the effect of chondrogenesis and exhibited promising strategy for cartilage tissue engineering therapies. J. Cell. Biochem. 118: 3607–3615, 2017.

BACKGROUND:We explored the effect of parathyroid hormone (PTH)-induced bone marrow stem cells (BMSCs) complexed with fibrin glue (FG) in the repair of articular cartilage injury in rabbits. MATERIAL AND METHODS:Forty-eight rabbits randomized into fou...

Both decalcified bone matrix (DBM) and fibrin gel possess good biocompatibility, so they are used as scaffolds to culture bone marrow mesenchymal stem cells (BMSCs). The feasibility and efficacy of using compound material being made of decalcified bone matrix and fibrin gel as a three-dimensional scaffold for bone growth were investigated. BMSCs were isolated from the femur of rabbit, then seeded in prepared scaffolds after incubation for 28 days in vitro. In vivo: 30 New Zealand White Rabbits received bone defect in left radius and divided three treatment groups randomly: (1) BMSCs/decalcified bone matrix/fibrin glue as experimental group; (2) decalcified bone matrix/fibrin glue without cells as control group; (3) nothing was implanted into the bone defects as blank group. The observation period of specimens was 12 weeks, and were analyzed bone formation in terms of serum proteomics (2D-PAGE and MALDI-TOF-TOF-MS), hematoxylin–eosin (HE) staining, ALP staining, and Osteopontin immunofluorescence detection. The experimental group present in three peculiar kinds of proteins, whose Geninfo identifier (GI) number were 136466, 126722803, and 126723746, respectively, correspond to TTR protein, ALB protein, RBP4 protein, and the histological inspections were superior to the other group. The content of osteopontin in experimental group was significantly higher than control group (p < 0.05). The overall results indicated that a combined material being made of BMSCs/decalcified bone matrix/fibrin glue can result in successful bone formation and decalcified bone matrix/fibrin glue admixtures can be used as a scaffold for bone tissue engineering. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1294–1304, 2014.

Purpose We investigated the contact pressure and area of the patellofemoral joint both before and after different meniscectomies to provide a biomechanical basis for selecting meniscectomy and its clinical application for meniscus injuries. Methods Six fresh cadaveric knees were used in the study. Using Staubli robots and an ultra-low-min-type pressure-sensitive tablet, changes in contact area and stress in the patellofemoral joint were measured at various flexion angles following different parts and degrees of meniscectomy. Results The patellofemoral contact area enlarged with the increase of knee flexion angle. From the values obtained from contact areas and average contact pressure of the patellofemoral joint, we found no significant difference between partial meniscectomy and intact knees, but a significant difference was found between total meniscectomy and intact knees. The contact area after lateral meniscectomy was statistically less than that of intact knees. The mean patellofemoral contact pressure after lateral meniscectomy was larger than in intact knees at each angle of flexion. No significant difference in contact area was observed between intact knees and medial meniscectomy. The average patellofemoral contact pressure after medial meniscectomy was larger than in intact knees from 0° ~ 30° of knee flexion, and no significant differences were found between intact knees and medial meniscectomy while knee bending from 60° to 90°. Conclusions Different meniscectomies result in high contact pressure or disordered distribution of contact pressure, which may be the cause of postoperative patellofemoral degenerative arthrosis.

Study Design. A histologic study of recombinant human bone morphogenetic protein-2/calcium phosphate cement (rhBMP-2/CPC) using adult rhesus monkeys in vivo. Objective. To evaluate the histologic changes of rhBMP-2/CPC in vertebroplasty and determine the feasibility of this bone substitution instead of polymethylmethacrylate (PMMA). Summary of Background Data. Previous studies have shown that the new rhBMP-2/nanoscale CPC has a suitable strength and injection for vertebroplasty. However, the osteoinductive properties and biodegradable characteristics are still unclear. Methods. Percutaneous vertebroplasty (PVP) was performed in 4 adult rhesus monkeys of 2 groups. Ten vertebral bodies (VBs) from T10–L7 of each rhesus were selected, and the 20 VBs in each group were randomly divided into 3 subgroups. Subgroup A (rhBMP-2/CPC): 8 VBs, filled with rhBMP-2/CPC; Subgroup B (PMMA): 6 VBs, filled with injectable PMMA; Subgroup C (control): 6 VBs, filled with normal saline. The 2 rhesus monkeys from each of the groups were killed at 2 and 6 months after operation, respectively. Individual specimens from the 40 VBs were collected for histologic observation. Results. In subgroup A, radiographic and histologic observations showed that the part of the rhBMP-2/CPC cement degraded with new bone and new vessel ingrowths, into the material, after 2 months. In addition, gaps, fibrous hyperplasia, or sclerotic callus were not found in the interface. After 6 months, the cement was nearly all replaced by mature bone tissue. In subgroup B, the inflammatory cell infiltration and fibrous membrane gapping were found after 2 months, and subsided partly at 6 months. But no new bone formation and material degradation were discovered. In subgroup C, the tunnels were filled with irregular new trabeculae after 2 months and unrecognizable from the surrounding mature bone after 6 months. Conclusion. It is confirmed that the rhBMP-2/CPC is an osteoinductive and biodegradable material (in animal trials). It may also be an alternative to PMMA in order to achieve biostabilization in a vertebroplasty.

A biomechanical study to evaluate the effects of a biodegradable calcium phosphate (Ca-P) bone substitute on the fixation strength and bending rigidity of vertebral body screws. To determine if an injectable, biodegradable Ca-P bone substitute provides significant augmentation of anterior vertebral screw fixation in the osteoporotic spine. Polymethylmethacrylate (PMMA) augmented screws have been used clinically; however, there is concern about thermal damage to the neural elements during polymerization of the PMMA as well as its negative effects on bone remodeling. Injectable, biodegradable Ca-P bone substitutes have shown enhanced fixation of pedicle screws. Sixteen fresh cadaveric thoracolumbar vertebrae were randomly divided into two groups: control (no augmentation) (n = 8) and Ca-P bone substitute augmentation (n = 8) groups. Bone–screw fixation rigidity in bending was determined initially and after 105 cycles, followed by pullout testing of the screw to failure to determine pullout strength and stiffness. The bone–screw bending rigidity for the Ca-P bone substitute group was significantly greater than the control group, initially (58%) and after cyclic loading (125%). The pullout strength for Ca-P bone substitute group (1848 ± 166 N) was significantly greater than the control group (665 ± 92 N) (P < 0.01). Stiffness in pullout for the Ca-P bone substitute groups (399 ± 69 N/mm) was significantly higher than the control group (210 ± 51 N/mm) (P < 0.01). This study demonstrated that augmentation of anterior vertebral body screw fixation with a biodegradable Ca-P bone substitute is a potential alternative to the use of PMMA cement.

A biomechanical study comparing two materials for augmentation of osteoporotic vertebral bodies and vertebral bodies after compression fracture. To compare an injected, biodegradable calcium phosphate bone substitute with injected polymethylmethacrylate bone cement for strengthening osteoporotic vertebral bodies and improving the integrity of vertebral compression fractures. Injection of polymethylmethacrylate bone cement into fractured vertebral bodies has been used clinically. However, there is concern about thermal damage to the neural elements during polymerization of the polymethylmethacrylate bone cement as well as its negative effects on bone remodeling. Biodegradable calcium phosphate bone substitutes have been studied for enhancement of fixation in fractured vertebrae. Forty fresh osteoporotic thoracolumbar vertebrae were used for two separate parts of this study: 1) injection into osteoporotic vertebrae: intact control (n = 8), calcium phosphate (n = 8), and polymethylmethacrylate bone cement (n = 8) groups. Each specimen then was loaded in anterior compression until failure; 2) injection into postfractured vertebrae: calcium phosphate (n = 8) and polymethylmethacrylate bone cement (n = 8) groups. Before and after injection, the specimens were radiographed in the lateral projection to determine changes in vertebral body height and then loaded to failure in anterior bending. For intact osteoporotic vertebrae, the average fracture strength was 527 ± 43 N (stiffness, 84 ± 11 N/mm), 1063 ± 127 N (stiffness, 157 ± 21 N/mm) for the group injected with calcium phosphate, and 1036 ± 100 N (stiffness, 156 ± 8 N/mm) for the group injected with polymethylmethacrylate bone cement. The fracture strength and stiffness in the calcium phosphate bone substitute group and those in the polymethylmethacrylate bone cement group were similar and significantly stronger than those in intact control group (P < 0.05). For the compression fracture study, anterior vertebral height was increased 58.5 ± 4.6% in the group injected with calcium phosphate and 58.0 ± 6.5% in the group injected with polymethylmethacrylate bone cement as compared with preinjection fracture heights. No significant difference between the two groups was found in anterior vertebral height, fracture strength, or stiffness. This study demonstrated that the injection of a biodegradable calcium phosphate bone substitute to strengthen osteoporotic vertebral bodies or improve vertebral compression fractures might provide an alternative to the use of polymethylmethacrylate bone cement.