The use of exogenous scaffolds to engineer bone tissue faces several drawbacks including insufficient biological activity, potential immunogenicity, elevated inflammatory reaction, fluctuating degradation rate, and low cell‐attachment efficiency. To circumvent these limitations, we sought to engineer large scaffold‐free bone tissue using cell sheets. We harvested intact cell sheets from bone marrow stromal cells using a continuous culture method and a scraping technique. The cell sheets were then rolled and fabricated into large constructs. Finally, the constructs were implanted into the subcutaneous pockets of nude mice. The cells within the sheet maintained in vitro osteogenic potential after osteoblast differentiation. Computed tomography scans and histological examination confirmed new bone formation in vivo. Additionally, the engineered bone exhibited enhanced compressive strength. Our results indicate that the BMSC sheets can facilitate the formation of functional three‐dimensional bone tissue without the use of exogenous scaffolds. Hence, the study provides an intriguing alternative strategy for bone repair. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:697–702, 2010

The reconstruction of bone defects remains a significant clinical problem. In this study, we constructed cell sheet from bone marrow stromal cells on normal culture plates by a simple method. The cell sheets showed evident mineralized nodules, high alkaline phosphatase activities, indicating their in vitro osteogenic potential. Then its osteogenic capability to heal critical-size rabbit calvarial defect was investigated. Forty adult New Zealand White rabbits were randomly divided into 4 groups of 10 animals each: (1) empty, (2) demineralized bone matrix (DBM) alone, (3) DBM/cell suspension, and (4) DBM/cell sheet. Specimens were harvested 6 and 12 weeks after implantation, respectively. Radiographic, histologic, and histomorphometric analyses were performed to evaluate the new bone formation inside the defect. The results revealed that the defect treated with DBM/cell sheet showed significantly more bone formation than other 3 groups (P < 0.05). Our study indicates that the cell sheet enhances bone regeneration in healing critical-size rabbit calvarial defect, and cell sheet-based engineered bone might be considered as potential substitutes for bone reconstruction.

Effective methods to shorten the treatment period of distraction osteogenesis (DO) are needed. To investigate whether injections of osteogenic bone marrow stromal cell (BMSC) sheet fragments could be used to facilitate new bone formation during DO, 30 rabbits underwent bilateral mandibular osteotomy and their mandibles were lengthened at a rate of 0.75 mm/12 h for 6 days after a 5‐day latency period. There were three treatment groups (n = 10 for each group): Serum‐free medium, dissociated BMSCs, and BMSC sheet fragments. A local injection was conducted with a needle directly into the distracted areas immediately after distraction. Rabbits were sacrificed for examination at 3 and 6 weeks after injection. Gross examination, radiographic evaluation, and micro‐CT scanning indicated a significant increase in bony union in the BMSC sheet fragment group, compared with the medium group and the dissociated cell group. The histomorphometric analysis showed more intensive bone formation in the sheet fragment group than the other two groups at each time point. Additionally, the peak load was significantly higher in the fragment group than those in the others. The results show that injection of BMSC sheet fragments promotes bone formation in DO and indicate a promising approach to shorten the treatment period of osteodistraction. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1082–1088, 2013

The skeleton is an important organ in the human body. Bone defects caused by trauma, inflammation, tumors, and other reasons can impact the quality of life of patients. Although the skeleton has a certain ability to repair itself, the current most effective method is still autologous bone transplantation due to factors such as blood supply and defect size. Modern medicine is attempting to overcome these limitations through cell therapy, with mesenchymal stem cells (MSCs) playing a crucial role. MSCs can be extracted from different tissues, and their differentiation potential varies depending on the source. Various cells and cell secretions can influence this process. This article, based on previous research, reviews the effects of macrophages, endothelial cells (ECs), nerve cells, periodontal cells, and even some bacteria on MSC osteogenic differentiation, aiming to provide a reference for multicell coculture strategies related to osteogenesis.

Bone regeneration materials combined with EGCG include natural polymer, synthetic polymer, bioceramic, metal, hydrogel and metal–EGCG networks. Currently, the above materials have been widely studied in the field of medicine.