Chitosan is a biocompatible polymer that has been widely studied for tissue engineering purposes. The aim of this research was to assess bone regenerative properties of an injectable chitosan and calcium phosphate-based composite and identify optimal degree of deacetylation (%DDA) of the chitosan polymer. Drill holes were generated on the left side of a mandible in Sprague-Dawley rats, and the hole was either left empty or filled with the implant. The animals were sacrificed at several time points after surgery (7-22 days) and bone was investigated using micro-CT and histology. No significant new bone formation was observed in the implants themselves at any time points. However, substantial new bone formation was observed in the rat mandible further away from the drill hole. Morphological changes indicating bone formation were found in specimens explanted on Day 7 in animals that received implant. Similar bone formation pattern was seen in control animals with an empty drill hole at later time points but not to the same extent. A second experiment was performed to examine if the %DDA of the chitosan polymer influenced the bone remodeling response. The results suggest that chitosan polymers with %DDA between 50 and 70% enhance the natural bone remodeling mechanism.

中文翻译：

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壳聚糖和磷酸钙基复合材料的骨重塑效果。

壳聚糖是一种生物相容性聚合物，已被广泛研究用于组织工程目的。这项研究的目的是评估可注射的壳聚糖和磷酸钙基复合材料的骨再生特性，并确定壳聚糖聚合物的最佳脱乙酰度（％DDA）。在Sprague-Dawley大鼠的下颌骨的左侧产生钻孔，钻孔要么留空要么用植入物填充。在手术后的几个时间点（7-22天）处死动物，并使用微型CT和组织学研究骨骼。在任何时间点，植入物本身均未观察到明显的新骨形成。然而，在远离钻孔的大鼠下颌骨中观察到大量新的骨形成。在接受植入物的动物中，在第7天植入的标本中发现了表明骨骼形成的形态学变化。在较晚的时间点在有空孔的对照动物中观察到相似的骨形成模式，但程度不同。进行第二个实验，以检查壳聚糖聚合物的％DDA是否影响骨重塑反应。结果表明，％DDA在50％至70％之间的壳聚糖聚合物可增强天然骨重构机制。