| Summary: | 碩士 === 國立成功大學 === 口腔醫學研究所 === 101 === Collagen gels have been applied as a scaffold material for tissue engineering. Recent approaches have provided evidence about the use of collagen matrix promoting the reparative process of damaged dental pulp tissue. The untreated collagen is stabilized by the weak intermolecular hydrogen and noncovalent bonds, which are weak to resist the mechanical loading and easily degraded by enzyme. There have been chemical agents such as glutaraldehyde (GTA) to promote the cross-linking. Alternatively, the photo activated cross-linking by rose Bengal (RB) or riboflavin (RF) accompanying with visible light (VL) or ultraviolet (UVA) has been also developed. This study purpose was to examine the biological effects of photoreactive collagen matrix as a reparative material on dental pulp cell.
The first parts were to examine the degrees of collagen crosslinking in different photoreactive materials and chemical reagent. RB and RF were mixed with collagen and subsequently irradiated by VL and UVA. The SDS-PAGE and contact angle were used to analyze the cross-linking of collagen. The all of results showed that whether the chemical or photoreactive cross-linked were able to promote the collagen cross-linking effectively.
The next were not only to investigate the effect of cross-linking agents and light irradiation, but also to examine the cytocompatibility of cross-linked collagen on human dental pulp cells. The data demonstrated that all of the cross-linking agents did not have cell cytotoxicity to HDPCs after culture for 7 days. Additionally, neither the visible light nor ultraviolet irradiation caused cell death. We also examined the adhesion and cytotoxicity of cross-linked collagen. The RF/UVA treated collagen showed comparable cell adhesion with the control. The other side, collagen cross-linked by photochemical was not significant toxicity to HDPCs when after culture for 5 days. However, the widely cross-linker of GTA that were significant produced cytotoxicity
Finally, we chosen 0.01% RB and 0.1% RF mixed collagen, and irradiated with either VL or UVA for following differentiation and mineralization tests. The cells plated on photo-crosslinked collagen matrix exhibited high ALP activity. The highest expressed ALP activity was found in 0.01% RB group. On the mineralization assay, there appeared calcium nodules when using riboflavin to promote collagen cross-linking. However, group of RF/VL exhibited more calcium nodules after culture for 21 days. 0.01% RB also presented mionor collagen degradation after 7-day cell culture, which was contributed to the inhibited MMP activity of RF.
This study explores the potential of photoreactive collagen matrix as a reparative agent on dental pulp cells. Among the crosslinkers, RF shows low cytotoxicity, high mineralization ability, and anti-degradation ability. Therefore, the application of photo reactive collagen cross linking with RF may benefit the dental pulp regeneration.
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