Stem cell-encapsulating hydrogel microbeads of several hundred microns in size suitable for injection, that could quickly degrade to release the cells, are currently unavailable. The objectives of this study were to: (1) develop oxidized alginate-fibrin microbeads encapsulating human umbilical cord mesenchymal stem cells (hUCMSCs); (2) investigate microbead degradation, cell release, and osteogenic differentiation of the released cells for the first time. Three types of microbeads were fabricated to encapsulate hUCMSCs: (1) Alginate microbeads; (2) oxidized alginate microbeads; (3) oxidized alginate-fibrin microbeads. Microbeads with sizes of about 100–500 µm were fabricated with 1×106 hUCMSCs/mL of alginate. For the alginate group, there was little microbead degradation, with very few cells released at 21 d. For oxidized alginate, the microbeads started to slightly degrade at 14 d. In contrast, the oxidized alginate-fibrin microbeads started to degrade at 4 d and released the cells. At 7 d, the number of released cells greatly increased and showed a healthy polygonal morphology. At 21 d, the oxidized alginate-fibrin group had a live cell density that was 4-fold that of the oxidized alginate group, and 15-fold that of the alginate group. The released cells had osteodifferentiation, exhibiting highly elevated bone marker gene expressions of ALP, OC, collagen I, and Runx2. Alizarin staining confirmed the synthesis of bone minerals by hUCMSCs, with the mineral concentration at 21 d being 10-fold that at 7 d. In conclusion, fast-degradable alginate-fibrin microbeads with hUCMSC encapsulation were developed that could start to degrade and release the cells at 4 d. The released hUCMSCs had excellent proliferation, osteodifferentiation, and bone mineral synthesis. The alginate-fibrin microbeads are promising to deliver stem cells inside injectable scaffolds to promote tissue regeneration.

Calcium phosphate cement (CPC) has in situ-setting ability and excellent osteoconductivity. Human embryonic stem cells (hESCs) are exciting for regenerative medicine due to their strong proliferative ability and multilineage differentiation capability. However, there has been no report on hESC seeding with CPC. The objectives of this study were to obtain hESC-derived mesenchymal stem cells (hESCd-MSCs), and to investigate hESCd-MSC proliferation and osteogenic differentiation on novel CPC with chitosan immobilized with RGD (CPC-chitosan-RGD). RGD was covalently bonded with chitosan, which was then incorporated into CPC. The CPC-chitosan-RGD scaffold had higher strength and toughness than CPC-chitosan control without RGD ( p < 0.05). hESCs were cultured to form embryoid bodies (EBs), and the MSCs were then migrated out of the EBs. Flow cytometry indicated that the hESCd-MSCs expressed typical surface antigen profile of MSCs. hESCd-MSCs had good viability when seeded on CPC scaffolds. The percentage of live cells and the cell density were significantly higher on CPC-chitosan-RGD than CPC-chitosan control. Scanning electron microscope examination showed hESCd-MSCs with a healthy spreading morphology adherent to CPC. hESCd-MSCs expressed high levels of osteogenic markers, including alkaline phosphatase, osteocalcin, collagen I, and Runx2. The mineral synthesis by the hESCd-MSCs on the CPC-chitosan-RGD scaffold was twice that for CPC-chitosan control. In conclusion, hESCs were successfully seeded on CPC scaffolds for bone tissue engineering. The hESCd-MSCs had good viability and osteogenic differentiation on the novel CPC-chitosan-RGD scaffold. RGD incorporation improved the strength and toughness of CPC, and greatly enhanced the hESCd-MSC attachment, proliferation, and bone mineral synthesis. Therefore, the hESCd-MSC-seeded CPC-chitosan-RGD construct is promising to improve bone regeneration in orthopedic and craniofacial applications.

To evaluate clinically and radiographically an alveolar ridge, preservation technique with deproteinized bovine bone graft and absorbable collagen membrane and then restoration with delayed implants were done. The study included 30 patients. The trial group's sockets were filled with deproteinized bovine bone graft (Bio-Oss) and covered with absorbable collagen membrane (Bio-Gide). The control group's sockets healed without any treatment. Panoramic radiograph and computed tomography were taken immediately after graft and 3 and 6 months later to evaluate the height, width, and volume change of the alveolar ridge bone. Dental implants were inserted in all sockets at 6 months, and osseointegration condition was evaluated in the following 12 months. All sockets healed uneventfully. In the trial group, the mean (SD) height reduction of the alveolar ridge bone was 1.05 (0.24) mm at 3 months and 1.54 (0.25) mm at 6 months. The width reduction was 1.11 (0.13) mm at 3 months and 1.84 (0.35) mm at 6 months. Bone volume reduction was 193.79 (21.47) mm at 3 months and 262.06 (33.08) mm at 6 months. At the same trend, in the control group, the bone height reduction was 2.12 (0.15) mm at 3 months and 3.26 (0.29) mm at 6 months. The width reduction was 2.72 (0.19) mm at 3 months and 3.56 (0.28) mm at 6 months. Bone volume reduction was 252.19 (37.21) mm at 3 months and 342.32 (36.41) mm at 6 months. There was a significant difference in alveolar ridge bone height, width, and volume reduction in the 2 groups. The osseointegration condition had no significant difference between the 2 groups. This study suggested that the deproteinized bovine bone graft and absorbable collagen membrane were beneficial to preserve the alveolar ridge bone and had no influence on the osseointegration of delayed implant.

Calcium phosphate cement (CPC) can fill complex-shaped bone defects and set in situ to form a scaffold with intimate adaptation to neighboring bone. The objectives of this study were to determine (1) the effects of fiber length and alginate microbead volume fraction on CPC mechanical properties, and (2) the effect of cell seeding density of human umbilical cord mesenchymal stem cells (hUCMSCs) on their proliferation and osteodifferentiation on CPC. Adding microbeads to CPC degraded the strength. However, increasing the fiber length improved the mechanical properties. Strength and elastic modulus of CPC-microbead-fiber scaffold matched those reported for cancellous bone. When the cell seeding density was increased from 50k to 300k, the cell viability, osteodifferentiation, and bone mineral synthesis also increased. When the seeding density was further increased to 500k, the osteodifferentiation and mineralization decreased. Hence, the 300k seeding density was optimal for CPC-microbead-fiber under the specified conditions. At day 8, alkaline phosphatase (ALP) gene expression of hUCMSCs with seeding density of 300k was threefold the ALP at 150k, and 200-fold the ALP at 50k. At day 14, osteocalcin and runt-related transcription factor 2 with cell seeding density of 300k was fourfold those at 50k. At day 14, mineralization by hUCMSCs at seeding density of 300k was 5-fold the mineralization at 150k, and 25-fold that at 50k. In conclusion, the effect of stem cell seeding density on CPC was determined for the first time. At low cell densities, cell viability and mineralization increased with seeding density. However, a higher seeding density was not necessarily better, and an optimal seeding density on CPC resulted in the best osteodifferentiation and mineralization. The stem cell-seeded CPC-fiber scaffold with excellent osteodifferentiation and mineralization is promising for orthopedic and craniofacial applications.

The need for bone repair has increased as the population ages. The objectives of this study were to (1) develop a novel biofunctionalized and macroporous calcium phosphate cement (CPC) containing alginate-fibrin microbeads encapsulating human umbilical cord mesenchymal stem cells (hUCMSCs); and (2) investigate hUCMSC proliferation and osteogenic differentiation inside CPC for the first time. Macroporous CPC was developed using calcium phosphate powders, chitosan, and gas-foaming porogen. Five types of CPCs were fabricated: CPC control, CPC + 0.05% fibronectin (Fn), CPC + 0.1% Fn, CPC + 0.1% Arg-Gly-Asp (RGD), and CPC + 0.1% Fn + 0.1% RGD. Alginate-fibrin microbeads containing 106 hUCMSCs/mL were encapsulated in the CPC paste. After CPC had set, the degradable microbeads released hUCMSCs inside CPC. hUCMScs proliferated inside CPC, with cell density at 21 d being 4-fold that at 1 d. CPC + 0.1% RGD had the highest cell density, which was 4-fold that of CPC control. The released cells differentiated into the osteogenic lineage and synthesized bone minerals. hUCMSCs inside the CPC + 0.1% RGD construct had gene expressions of alkaline phosphatase (ALP), osteocalcin (OC) and collagen I, which were twice those of CPC control. Mineral synthesis by hUCMSCs inside the CPC + 0.1% RGD construct was 2-fold that in CPC control. RGD and Fn incorporation in CPC did not compromise the strength of CPC, which matched the reported strength of cancellous bone. In conclusion, degradable microbeads released the hUCMSCs which proliferated, differentiated and synthesized minerals inside the macroporous CPC for the first time. CPC with RGD greatly enhanced cell functions. The novel biofunctionalized and macroporous CPC-microbead-hUCMSC construct is promising for bone tissue engineering applications.

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Objectives: To review the cases of accidental aspiration and ingestion of foreign objects during dental procedure, and to emphasize the importance of thorough documentation of the accidents. Methods: A comprehensive search on (dental procedure/treatment/practice), (aspiration/inhalation), and (ingestion/ swallow) was performed for all years before 1st October 2014 available. The statistic analysis was made on the variables including journals and reported year, patients' age, gender, general conditions, dental procedure and location for procedure, foreign objects, site of involvement, possible causes, anesthesia during procedure and treatment, symptoms, treatment time and treatment modality, follow-up, and so on. Results: A total of 617 cases reported by 45 articles from 37 kinds of journals were included and analyzed. Most reports made detailed record. While some important variables were recorded incompletely, including patient's general conditions, location for procedure, clinical experience of the involving dentists, tooth position of procedure, possible causes, and anesthesia during procedure and treatment for the accident. Conclusions: Aspiration and ingestion of foreign objects are rare and risky complication during dental procedure. Each accident should have thorough documentation so as to provide enough information for the treatment and prevention.

Tissue engineering approaches are promising to meet the increasing need for bone regeneration. Calcium phosphate cement (CPC) can be injected and self-set to form a scaffold with excellent osteoconductivity. The objectives of this study were to develop a macroporous CPC-chitosan-fiber construct containing alginate-fibrin microbeads encapsulating human umbilical cord mesenchymal stem cells (hUCMSCs) and to investigate hUCMSC release from the degrading microbeads and proliferation inside the porous CPC construct. The hUCMSC-encapsulated microbeads were completely wrapped inside the CPC paste, with the gas-foaming porogen creating macropores in CPC to provide for access to culture media. Increasing the porogen content in CPC significantly increased the cell viability, from 49% of live cells in CPC with 0% porogen to 86% of live cells in CPC with 15% porogen. The alginate-fibrin microbeads started to degrade and release the cells inside CPC at 7 days. The released cells started to proliferate inside the macroporous CPC construct. The live cell number inside CPC increased from 270 cells/mm 2 at 1 day to 350 cells/mm 2 at 21 days. The pore volume fraction of CPC increased from 46.8% to 78.4% using the gas-foaming method, with macropore sizes of approximately 100 to 400 mm. The strength of the CPC-chitosan-fiber scaffold at 15% porogen was 3.8 MPa, which approximated the reported 3.5 MPa for cancellous bone. In conclusion, a novel gas-foaming macroporous CPC construct containing degradable alginate-fibrin microbeads was developed that encapsulated hUCMSCs. The cells had good viability while wrapped inside the porous CPC construct. The degradable microbeads in CPC quickly released the cells, which proliferated over time inside the porous CPC. Self-setting, strong CPC with alginate-fibrin microbeads for stem cell delivery is promising for bone tissue engineering applications.