Atelocollagen Scaffold Enhances Cartilage Regeneration in Osteochondral Defects: A Study in Rabbits.

BACKGROUND: To enhance articular cartilage healing, microfractures (Mfx) and bone marrow aspirate concentrate (BMAC) are commonly used, and some form of scaffold is often used together to increase its efficacy. Herein, we compared the efficacy of atelocollagen scaffold to that of collagen scaffold when used with Mfx or BMAC on osteochondral defect of animal. METHODS: This experiment was designed in two stages, and therapeutic effects of Mfx and BMAC were respectively evaluated when used with atelocollagen or collagen scaffold. Femoral condyle defects were artificially created in male New Zealand White rabbits, and in each stage, 12 rabbits were randomly allocated into three treatment groups: test group with additional atelocollagen scaffold, the positive control group with collagen scaffold, and the negative control group. Then, for 12 weeks, macroscopic and histological evaluations were performed. RESULTS: At 12 weeks, defects in the test group were fully regenerated with normal cartilage-like tissue, and were well integrated with the surrounding cartilage at both stages experiment, whereas defects in the control groups were not fully filled with regenerated tissue, and the tissue appeared as fibrous tissue. Histologically, the regenerated tissue in the test group showed a statistically significant improvement compared to the positive and negative control groups, achieving a similar structure as normal articular cartilage. CONCLUSION: The results showed that implantation of the atelocollagen scaffold enhanced cartilage regeneration following osteochondral defects in rabbits. This suggests that the atelocollagen scaffold can be used with Mfx or BMAC for effective regeneration of osteochondral defects.

Intra-Articular Atelocollagen Injection for the Treatment of Articular Cartilage Defects in Rabbit Model.

BACKGROUND: Atelocollagen is widely recognized as a biomaterial for regenerative medicine because of its good compatibility and low antigenicity. Injury of the outermost layer of articular cartilage, known as the lamina splendens, can lead to osteoarthritis (OA) and eventually full-thickness cartilage loss. The intra-articular injection of atelocollagen has been designed to restore the cartilage layer and cartilage defects in OA joints. In this study, we investigated the efficacy of atelocollagen as a cartilage supplement for joint defects. METHODS: In this study, we evaluated the therapeutic effects of atelocollagen in animals with cartilage defects. Femoral groove defects were artificially created in 12 male New Zealand white rabbits, which were treated with intra-articular injection of either atelocollagen (experimental) or normal saline (control). The results were observed 3, 6, 9, and 12 weeks following macroscopic and histological evaluations. RESULTS: At 3 weeks, cartilage tissue was restored in the experimental group, whereas the control group did not show signs of restoration. At 12 weeks, defects in both groups were filled with regenerated tissue, but the experimental group displayed a morphologically better appearance. Histologically, the regenerated tissue in the experimental group showed statistically significant improvement compared to the control group, with a structure similar to that of normal articular cartilage. CONCLUSION: The results showed that the intra-articular injection of atelocollagen enhanced cartilage regeneration following rabbit patellar groove defects. Therefore, intra-articular injection of atelocollagen can be used as an effective supplement for joint defects.

Embryonic inbreeding depression varies among populations and by mating system in Witheringia solanacea (Solanaceae).

PREMISE OF THE STUDY: Embryonic inbreeding depression is a key influence on mating system evolution and can be difficult to estimate in self-incompatible species. A pollen chase experiment was used to estimate the magnitude of embryonic inbreeding depression in Costa Rican Witheringia solanacea, a species polymorphic for self-incompatibility (SI). In a pollen chase experiment, bud self-pollinations are followed after anthesis by outcross pollinations, with a comparable pair of outcross pollinations used as a control. Lowered seed set for the self-precedence treatment indicates embryonic inbreeding depression. • METHODS: Embryonic inbreeding depression was assayed for self-compatible (SC) individuals and for SI plants from two populations that differ quantitatively in the onset and enzymatic activity of their SI response. Microsatellite markers were used to assay the selfing rate of a sample of surviving progeny from the prior self-pollination treatment. • KEY RESULTS: SC individuals showed no evidence of embryonic inbreeding depression. In SI plants, prior self-pollination reduced seed number by 28-70%, depending on population. Microsatellite genotyping revealed that embryonic inbreeding depression was even more severe than estimated by the phenotypic data: for mature fruits resulting from self-pollination precedence, the majority of the progeny were the result of outcross fertilization. • CONCLUSIONS: Lineage-specific purging of recessive lethals has accompanied the evolution of SC in this species. SI populations show contrasting levels of embryonic inbreeding depression, with nearly complete embryonic lethality upon selfing in the Monteverde population. In the face of high embryonic inbreeding depression, an increase in selfing rate can evidently occur only under severe pollen limitation.