The physis is a cartilaginous tissue in children's long bones that is responsible for bone elongation. Physeal injuries can heal with bony repair tissue known as a “bony bar,” and this can cause growth deformities. Current treatments involve surgical resection of the bony bar and insertion of inert materials in hopes of preventing bony bar re‐formation and preserving bone elongation. However, these materials frequently fail and the bony bar commonly returns. This study investigated alginate–chitosan hydrogels as interpositional materials to block bony bar formation in a rat model of physeal injury. Further, biomaterial properties such as substrate stiffness, permeability, and degradation rate were studied. Different ratio alginate:chitosan hydrogels with or without calcium cross‐linking were tested for their inhibition of bony bar formation and restoration of the injured physis. Alginate:chitosan were mixed (a) 90:10 with calcium (90:10 + Ca); (b) 50:50 with calcium (50:50 + Ca); (c) 50:50 without calcium (50:50 − Ca); and (d) 50:50 made with irradiated alginate (IA) and without calcium. We found that repair tissue was determined primarily by the in vivo degradation rate of alginate–chitosan hydrogels. 90:10 + Ca had a slow degradation rate, prevented cellular infiltration, and produced the most bony bar tissue while having softer, more permeable material properties. IA had the fastest degradation, showed high cellular infiltration, and produced the most cartilage‐like tissue while having stiffer, less permeable material properties. Our results suggest that the in vivo biomaterial degradation rate is a dynamic property that can be optimized to influence cell fate and tissue repair in physeal injuries.

中文翻译：

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海藻酸盐-壳聚糖水凝胶的体内降解率影响骨骺损伤后的组织修复。

骨骺是儿童长骨中的软骨组织，负责骨骼的伸长。骨骺损伤可以用被称为“骨棒”的骨修复组织愈合，这会导致生长畸形。目前的治疗包括手术切除骨杆和插入惰性材料，以期防止骨杆再形成和保持骨伸长。然而，这些材料经常失效并且骨棒通常会返回。本研究调查了海藻酸盐-壳聚糖水凝胶作为插入材料，以阻止大鼠骺骨损伤模型中的骨条形成。此外，还研究了生物材料特性，例如基材刚度、渗透性和降解率。不同比例海藻酸盐：测试了有或没有钙交联的壳聚糖水凝胶对骨条形成和损伤骨恢复的抑制。将海藻酸盐：壳聚糖与钙（90:10 + Ca）以 90:10 的比例混合；(b) 50:50 含钙 (50:50 + Ca)；(c) 50:50 不含钙 (50:50 − Ca)；(d) 50:50 用辐照藻酸盐 (IA) 制成，不含钙。我们发现修复组织主要由海藻酸盐-壳聚糖水凝胶的体内降解率决定。90:10 + Ca 具有缓慢的降解速度，可防止细胞浸润，并产生最多的骨条组织，同时具有更柔软、更具渗透性的材料特性。IA 降解速度最快，显示出高细胞浸润，并产生最多的软骨样组织，同时具有更硬、渗透性更低的材料特性。