A new fish scale-derived scaffold for corneal regeneration.

The purpose of this study is to develop a novel scaffold, derived from fish scales, as an alternative functional material with sufficient mechanical strength for corneal regenerative applications. Fish scales, which are usually considered as marine wastes, were acellularized, decalcified and fabricated into collagen scaffolds. The microstructure of the acellularized scaffold was imaged by scanning electron microscopy (SEM). The acellularization and decalcification treatments did not affect the naturally 3-dimentional, highly centrally-oriented micropatterned structure of the material. To assess the cytocompatibility of the scaffold with corneal cells, rabbit corneal cells were cultured on the scaffold and examined under SEM and confocal microscopy at different time periods. Rapid cell proliferation and migration on the scaffold were observed under SEM and confocal microscopy. The highly centrally-oriented micropatterned structure of the scaffold was beneficial for efficient nutrient and oxygen supply to the cells cultured in the three-dimensional matrices, and therefore it is useful for high-density cell seeding and spreading. Collectively, we demonstrate the superior cellular conductivity of the newly developed material. We provide evidences for the feasibility of the scaffold as a template for corneal cells growth and migration, and thus the fish scale-derived scaffold can be developed as a promising material for tissue-engineering of cornea.

Characterization and osteogenic effects of mesenchymal stem cells on microbeads composed of hydroxyapatite nanoparticles/reconstituted collagen.

Natural bone is comprised of nanosized blade-like crystals of hydroxyapatite grown in close contact with collagen (Col) fibers. Characteristics of artificial bone tissue differ considerably with those of natural ones, mainly from the unusual self-organizing interaction between the apatite crystals and the proteic components. Nanoparticle spheres of hydroxyapatite (n-HA), dispersed in reconstituted fibrous Col, were prepared in three weight ratios of 75:25, 65:35, and 50:50 (n-HA:Col). Bone marrow mesenchymal stem cells (MSCs) from rabbits were seeded and cultured on the n-HA/Col microbeads and characterized. n-HA were evenly distributed throughout the Col matrix and aggregated to microbeads as determined by scanning electron microscopy. Electron and confocal microscopy showed that the MSCs spread and attached to microbeads via focal adhesions, while staining for F-actin and DNA revealed the presence of stress fibers. The phenotype of the MSCs in the flow cytometry was identified as CD11a-, CD44+, and CD90.1+. The optimal weight ratio is 65:35 for the normalized alkaline phosphatase activities. The transduced MSCs, engineered by replication-defective adenovirus to express the BMP-2 gene, demonstrated synergic osteogenic effects in the microbeads. MSCs are capable of proliferating and differentiating in appropriate combinations of n-HA/Col. Thus it is a promising composite for future clinical applications.

Cranial repair using BMP-2 gene engineered bone marrow stromal cells.

BACKGROUND: Bone grafts, allografts, and biocompatible artificial bone substitutes all have their shortcomings when used for the repair of cranial bone defects. Tissue engineered bone shows promise as an alternative for the repair of these defects. MATERIALS AND METHODS: Rabbit bone marrow mesenchymal stromal cells (MSCs) were separated from iliac crest aspirates and expanded in a monolayer culture 1 month before implantation. These MSCs were then infected with replication-defective adenovirus-human BMP-2 genes 1 week before implantation. Bilateral critical-size cranial defects were created in the animal with removal of osteoinductive periosteum and dura. MSCs were mixed with alginate UP (ultrapure) to form MSC/polymer construct. MSCs used for the control site were infected with adenovirus beta-galactosidase (beta-gal). After 1 week, 6 weeks, and 3 months, five rabbits from each experimental group were sacrificed and the cranial defect site was examined by histology study. RESULTS: Near-complete repair of the large size cranial defects using the tissue engineered MSC/alginate construct was observed. The H&E stain and von Kossa's staining should better regenerate bone at the experiment site. A statistically significant difference in bone formation was noted by 3D CT imaging at 3 months post-BMP-2 treatment of the cranial defects (0.79 +/- 0.06 versus 0.47 +/- 0.05 cm(2), P < 0.001) but not at 6 weeks (0.36 +/- 0.04 versus 0.33 +/- 0.03 cm(2), P = 0.347). CONCLUSIONS: Near-complete repair of large cranial defects can be achieved using tissue engineered bone. The use of newly developed polymers as well as the integration of the stem cell concept with gene medicine is necessary to attain this goal.