Intraglandular Transplantation of Adipose-Derived Stem Cells for the Alleviation of Irradiation-Induced Parotid Gland Damage in Miniature Pigs.

PURPOSE: In a previous study, the authors verified the protective efficacy of adipose-derived stem cells (ADSCs) on the prevention of salivary gland (SG) damage induced by irradiation in mice. As a critical step before implementation in clinical practice, the present study investigated the protective effect of ADSCs in a miniature pig SG model, because miniature pigs share many characteristics with humans. MATERIALS AND METHODS: Third-passage autologous ADSCs at a concentration of 4 × 106 cells/mL were transplanted by intraglandular injection into parotid glands (PGs) immediately after local irradiation at a single dose of 20 Gy. The injection process was repeated twice a week for 6 consecutive weeks. At 12 weeks after irradiation, functional and histologic evaluations were performed by measuring salivary flow rate (SFR) and hematoxylin and eosin and periodic acid-Schiff staining. Immunohistochemical and transmission electron microscopic examinations also were conducted to evaluate amylase (AMY) production, microvessel density (MVD), and microstructural changes. RESULTS: The irradiated PGs showed remarkable decreases in SFR, AMY production, and MVD. However, transplantation of ADSCs alleviated irradiated PG morphology and function by preserving more functional acinar cells and increasing SFR and AMY production. In addition, greater MVD was observed in the ADSC-treated group than in the irradiated group. CONCLUSIONS: These results indicated that intraglandular transplantation of autologous ADSCs is an effective method to protect PGs against damage from irradiation in miniature pigs, which might have clinic application in the future.

Coculture of peripheral blood CD34+ cell and mesenchymal stem cell sheets increase the formation of bone in calvarial critical-size defects in rabbits.

The reconstruction of large bony defects remains a clinical challenge, and angiogenesis and neovascularisation are being given more attention in bone tissue engineering. In this study we cocultured peripheral blood CD34+ cells (PB-CD34+ cells), an endothelial progenitor cell/haematopoietic stem cell-enriched population, with bone marrow-derived mesenchymal stem cells (MSC) to investigate their potential for bony regeneration. Cocultured cells showed better osteogenic differentiation than MSC alone in vitro. The cocultured cells and MSC sheets were also composited with hydroxyapatite and implanted in calvarial critical-size defects in rabbits. The rabbits were killed before microcomputed tomographic (MicroCT) and histological analysis. The results showed that cocultured cell composites had promoted bony regeneration more efficiently by 8 weeks after implantation. Our results indicate that the coculture of PB-CD34+ cells and MSC increases bony regeneration in calvarial critical-size defects in rabbits, and provide a new promising therapeutic strategy to aid skeletal healing.

Effects of hyperbaric oxygen therapy on rapid tissue expansion in rabbits.

BACKGROUND: Tissue expansion has been widely used to provide additional soft tissue for clinical reconstruction. Rapid expansion requires a much shorter clinical period than conventional expansion; however, less natural skin growth occurs resulting in a larger stretch-back ratio and insufficient extra soft tissue for clinical use. In this study, hyperbaric oxygen therapy (HBOT) was used in the inflation phase of rapid expansion to increase natural skin growth. METHODS: Twelve rabbits were divided into two groups. Each group received rapid expander inflation every day. One group received HBOT and the other did not. Blood flow in the expanded skin of each rabbit was assayed in the 10-day inflation phase. After the inflation phase, a rectangular expanded flap of each rabbit was harvested. The instant stretch-back ratio, tension, weight and histological characteristics of the flaps were evaluated. RESULTS: (1) After the second inflation day, the mean blood flow of the HBOT group became significantly higher than that of the control with each day (P < 0.05). At the last day, the blood flow of the HBOT group increased to 131 ± 17 pu, while the control group decreased to 35 ± 5 pu. (2) The mean instant stretch-back ratio of the HBOT group under no-tension conditions was 29 ± 4%, which was significantly less than that of the control group, 46 ± 3% (P < 0.01). (3) The mean flap tension of the HBOT group was 15.3000 ± 1.47648 g and 12.9833 ± 0.73598 g in the transverse and longitudinal axis, respectively, both significantly smaller than that of the control group (33.9167 ± 4.78390 g and 26.5000 ± 2.45031 g, respectively) (P < 0.01). (4) Mean per unit flap weight of the HBOT group was 0.221 ± 0.005 g cm(-2), significantly heavier (P < 0.01) than that of the control group (0.143 ± 0.010 g cm(-2)). (5) Histologically, the epidermal layer and thickness of the expanded skin of the HBOT group were much thicker than those of the control group, and more vessels were visible in the subcutaneous tissue. CONCLUSIONS: The use of HBOT in the inflation phase of rapid expansion can effectively promote blood flow in the expanded skin, increase its natural skin growth and reduce the instant stretch-back ratio and tension of expanded skin.