In Vivo Biodegradability of PLLA and PLGA Sponge using Non-toxic Effevescent as a Porogen Additive

In many tissue engineering application, highly open porous scaffolds are required for efficient cell seeding and culture. Synthetic biodegradable polymers such as poly (L-lactic acid)(PLLA) and its copolymers with D-lactic and glycolic acids(PLGA) are widely used as a porous scaffold. The suitable biodegradability and dimensional stability of porous scaffolds during in vivo implantation play an important role in tissue engineering application. In this study, we investigated in vivo biodegradation and dimensional stability of acellular porous polymer scaffolds prepared by using a gas foaming technique with non-toxic effervescent mixture. In addition, we have engineered cartilage tissue 3D cultured on PLGA scaffolds in nude mouse in order to compare with degradation and deformation on acellular porous polymer scaffolds and to form tissue-engineered cartilage tissue. Sodium bicarbonate and citric acid crystals were used as an effervescent mixture. These particles were milled and sieved to yield various range of sizes(50 - 100, 100 - 300, and > 300 micrometer). After polymer scaffolds fabricated, biodegradation test was performed in subcutaneous tissue of male rats during 12 weeks. Degradability of polymer scaffolds were evaluated by weight difference, gel permeation chromatography(GPC), and SEM as each period. Tissue-engineered cartilage by transplanting 3D cultured chondrocytes onto PLGA 85:15 scaffolds in nude mouse was also made and compared with acellular scaffolds. In conclusion, highly open porous biodegradable scaffolds are prepared by gas foaming method using sodium bicarbonate and citric acid as a non-toxic effervescent mixture. Furthermore, tissue-engineered cartilage formation by in vivo 3D culture onto modified PLGA scaffolds in nude mouse was significantly improved as compared to controls.

Correction of the Nasal Hump considering the Height of the Nasal Root

Oriental hump nose is characterized by mild degree of the hump, broad dorsum, low nasal height and drooping tip. Therefore, conservative humpectomy followed by either tip-plasty or augmentation rhinoplasty yields more satisfactory results than classical Joseph's nasal hump reduction. However, the degree of the hump as well as the length of the nose can be affected by the height of the nasal root. That is, if the nasal root is too low, the hump nose may stand out and the nose will seem longer than the actual measurements. We think that it is important to consider the height of the nasal root in the course of the nasal hump reduction. During the last 2 year periods, we have classified twenty eight patients with hump nose into three groups, low(group A: 7 patients), moderate(group B: six patients) and high(group C: fifteen patients), based on the nasal root height. Each group went through different operative procedures according to their nasal root height and favorable results were obtained.