Osteogenic activity of MG63 cells on bone-like hydroxyapatite/collagen nanocomposite sponges.

The hydroxyapatite/collagen (HAp/Col) sponge with 95% (v/v) porosity was prepared by freeze-drying of a HAp/Col fiber suspension. MG63 cells were seeded onto the HAp/Col sponge and cultured under a pressure/perfusion condition with osteogenic supplements. A collagen (Col) sponge was used as a control. The cells with sponge were examined by a histology, total DNA content and gene expression. The cells showed good attachment and proliferation everywhere in the HAp/Col sponge, while the cells mainly proliferated at the peripheral part of the Col sponge. Thus, total DNA content in the HAp/Col sponges reached 1.8 times greater than that in the Col sponges at Day 21. Further, the cells and extracellular matrix only in the HAp/Col sponge were calcified, although the cells in both sponge evenly expressed osteogenic gene. These results suggest that the HAp/Col sponge could be useful as a scaffold for bone tissue engineering.

The effect of low reactive-level laser therapy (LLLT) with helium-neon laser on operative wound healing in a rat model.

The effect of low reactive-level laser therapy (LLLT) with a He-Ne laser on operative wound healing was investigated in a rat model. 10-millimeter surgical wounds were created on the backs of Sprague Dawley rats, and animals were assigned to one of eleven groups (n=5). Ten groups received either 8.5 mW or 17.0 mW irradiation of 15 seconds LLLT a day with one of five different irradiation frequencies, i.e. daily (from the 1st to 6th day following surgery), every other day (the 1st, 3rd, and 5th day), on only the 1st day, on only the 3rd day, and on only the 5th day; the 1st day was the day following the surgery. The control group received no irradiation. A skin specimen was harvested from the dorsal thoracic region on the 7th day to measure the rupture strength. The control group had the lowest rupture strength (5.01 N), and the 17.0 mW every other day irradiation group had the highest rupture strength (13.01 N). Statistical differences were demonstrated in the 8.5 mW irradiation setting between the every other day irradiation group and the control group (p<0.05); and in 17.0 mW irradiation setting between the every day irradiation, the every other day, and the 1st day only groups vs. the control group (p<0.01). Histological examination demonstrated that wound healing in the 17.0 mW every other day irradiation group was promoted most significantly such as the prevention of excessive inflammation, increased formation of collagen fibers, and recovery in continuity of tissues. The control group showed poor wound healing and the other experimental groups showed intermediate healing. Thus LLLT with a He-Ne laser was found to promote the healing of operative wounds in the present rat model, in which the most favorable application of LLLT was the 17.0 mW setting of 15 seconds a day with a frequency of every other day.

Development of a nerve scaffold using a tendon chitosan tube.

Bridge grafting (15 mm) into the sciatic nerve of SD rats was carried out using tendon chitosan tubes having either a circular or triangular cross-section, as well as triangular tubes combined with laminin, CDPGYIGSR, or CSRARKQAASIKVAVSAD (n = 15 in each group). As a control, isografting (15 mm) was carried out in the SD rats (n = 7). Specimens were taken after 1, 2, 4, 6, and 8 weeks for histology, and nerve regeneration was evaluated electro-physiologically and histologically after 12 weeks. The mechanical strength of triangular tubes was found to be higher than circular tubes, and the inner volume of a triangular tube tends to be larger than in circular tubes. Nerve tissue regeneration along the tube wall was found in both the laminin and laminin peptide groups. According to the result of percentage neural tissue in relation to evoked action potentials, the consecutive treatments of YIGSR and IKVAV was found to match the effectiveness of intact laminin.