Evaluation of bone regeneration in a critical size cortical bone defect in rat mandible using microCT and histological analysis.

GOAL: Evaluate bone regeneration in a critical size bone defect model in the jaw of healthy rats as a function of gender and defect location. DESIGN: A series of microCT and histological studies were performed to evaluate the process of bone regeneration in rats with a mandibular critical size defect. Rats were placed in two groups according to gender and sorted in terms of bone defect location. Bone regeneration rate and hydroxyapatite concentration were assessed with microCT imaging at specific times after surgery. Histological analysis was also performed to evaluate bone regeneration. RESULTS: No more that 85% of bone regeneration was observed after 60 days, with a low rate constant (K) indicating a slow restoration of the defect. Assessment of microCT images showed partial closure of the defect in all cases, which was confirmed by histological analysis. Hydroxyapatite concentration values revealed that regenerated bone was not fully calcified. No statistically significant differences in terms of gender or defect location were found. CONCLUSION: The defect model studied here, located in the jaw of healthy rats, shows potential as a preclinical critical size bone defect model to evaluate bone regeneration therapies in the fields of dentistry and maxillofacial surgery.

Viable pluripotent chick blastodermal cells can be maintained long term in an alkaline defined medium.

Most chicken embryonic cell culture methods call for neutral pH media of different natures, with disregard of the peculiar electrochemical environment in which avian embryos develop, with a 4 pH unit gradient across the thin blastoderm and the vitelline membrane. We report results of a culture system in alkaline media (pH >9) with atmospheric conditions. Blastodermal and blood cells, maintained for 8 wk with minor differentiation in the absence of the standard growth factors, developed a thick, mucoid-like matrix in which a large proportion of the cell mass grew embedded, with no direct contact to cultureware. After up to 8 wk, blastoderm explants and dissociated blastodermal cells, cultured in either M199 or Dulbecco's modified Eagle's medium (DMEM) in the absence of supplemental CO2, expressed several pluripotency markers (SSEA1, VASA) and embryoid bodies were formed. The assayed conditions impose an undoubted electrolyte stress on the cells which, notwithstanding, maintained their viability and remained undifferentiated. We hypothesize that a rise in pH and the activation of active cation exchanger like Na(+)/H(+) antiporter could mediate the observed differentiation arrest.

[Use of a composite prosthesis (PL-PU99) versus a biological prosthesis (Surgisis) in an experimental model of temporary abdominal closure]. / Estudio experimental comparativo entre una prótesis compuesta (PL-PU99) y una prótesis biológica (Surgisis) en el cierre temporal abdominal.

INTRODUCTION: In some diseases of peritoneal origin, temporary closure of the abdominal cavity is required to avoid compartmental syndrome. This allows normal intra-abdominal pressure to be maintained and the fascial edges to be preserved for subsequent definitive closure. MATERIAL AND METHOD: Defects (7 x 4 cm) were created in the anterior abdominal wall of New Zealand white rabbits and were repaired using an oval-shaped patch of a prosthesis designed by our team (PL-PU99) or a prosthesis of biological origin (Surgisis) of similar dimensions to the defects. The biomaterials were fixed to the cut edges of the wall by 2 polypropylene running sutures interrupted only at the corners, leaving the patch in contact with the atmosphere. Fourteen days after implantation, prosthesis/anchorage tissue specimens were taken for light and scanning electron microscopy, morphometric measurements and immunohistochemical macrophage identification (using the RAM-11 antibody). RESULTS: There were no cases of mortality or implant rejection. Small areas of loose adhesions were observed on some implants (covering 0.31 +/- 0.03% of the PL-PU99 implants and 31.60 +/- 7.35% of Surgisis). The neoperitoneum induced by both implant types was homogenous and well organized, with thicknesses of 427.60 +/- 8.38 microm (PL-PU99) and 171.99 +/- 18.70 microm (Surgisis). No significant differences were observed in terms of the macrophage reaction induced (PL-PU99 19.76 +/- 1.59%; Surgisis 21.07 +/- 8.93% macrophages). CONCLUSIONS: a) The PL-PU99 prosthesis provoked fewer adhesions and generated a thicker neoperitoneum. b) Both prostheses would probably be suitable for temporary closure of the abdominal cavity.