The use of a cartilage decellularized matrix scaffold for the repair of osteochondral defects: the importance of long-term studies in a large animal model.

OBJECTIVE: To investigate the effect of decellularized cartilage-derived matrix (CDM) scaffolds, by itself and as a composite scaffold with a calcium phosphate (CaP) base, for the repair of osteochondral defects. It was hypothesized that the chondral defects would heal with fibrocartilaginous tissue and that the composite scaffold would result in better bone formation. METHODS: After an 8-week pilot experiment in a single horse, scaffolds were implanted in eight healthy horses in osteochondral defects on the medial trochlear ridge of the femur. In one joint a composite CDM-CaP scaffold was implanted (+P), in the contralateral joint a CDM only (-P) scaffold. After euthanasia at 6 months, tissues were analysed by histology, immunohistochemistry, micro-CT, biochemistry and biomechanical evaluation. RESULTS: The 8-week pilot showed encouraging formation of bone and cartilage, but incomplete defect filling. At 6 months, micro-CT and histology showed much more limited filling of the defect, but the CaP component of the +P scaffolds was well integrated with the surrounding bone. The repair tissue was fibrotic with high collagen type I and low type II content and with no differences between the groups. There were also no biochemical differences between the groups and repair tissue was much less stiff than normal tissue (P < 0.0001). CONCLUSIONS: The implants failed to produce reasonable repair tissue in this osteochondral defect model, although the CaP base in the -P group integrated well with the recipient bone. The study stresses the importance of long-term in vivo studies to assess the efficacy of cartilage repair techniques.

Cochlear implantation in patients with compromised healing.

BACKGROUND: The indications for cochlear implantation (CI) are continually evolving and, as experience accumulates, the relative contraindications for CI continue to decrease. However, there is little information regarding CI in patients who may be considered to be at risk for poor wound healing due to immunosuppression or intercurrent disease. OBJECTIVE: To assess and report the complication rates, postoperative course, postimplant rehabilitation, and long-term performance of patients considered at risk due to presumably impaired healing capability. We hypothesized that these patients had outcomes similar to other implanted patients. METHODS: This is a retrospective chart review of 277 patients who have received CI at the University of Miami Ear Institute between 1990 and 1999. The clinical courses of 6 patients on immunosuppressive medications and 7 patients with diseases believed to be associated with poor healing are reported. RESULTS: Long-term follow-up (mean, 33 months) showed postoperative complication rates, performance, and rehabilitation compliance that were similar to published reports of noncompromised patients. CONCLUSION: CI of selected patients with potentially reduced healing capabilities is safe and effective.

A whole-genome assembly of Drosophila.

We report on the quality of a whole-genome assembly of Drosophila melanogaster and the nature of the computer algorithms that accomplished it. Three independent external data sources essentially agree with and support the assembly's sequence and ordering of contigs across the euchromatic portion of the genome. In addition, there are isolated contigs that we believe represent nonrepetitive pockets within the heterochromatin of the centromeres. Comparison with a previously sequenced 2.9- megabase region indicates that sequencing accuracy within nonrepetitive segments is greater than 99. 99% without manual curation. As such, this initial reconstruction of the Drosophila sequence should be of substantial value to the scientific community.