Evaluation of dynamic change in regenerated tendons in a mouse model

Abstract

BackgroundUsing the film model method, the process whereby a substance called tendon gel is secreted from transected tendon ends and changed into a tendon after application of a traction force is known. The objective of this study was to investigate the association between mechanical properties in the early stages of tendon regeneration and time by using the film model method.MethodAdult male ddY mice, closed colony mice established and maintained in Japan, were prepared for each experimental group. The study animals were 30 mice and were divided into three groups of 10 mice each. Ten specimens of tendon gel secreted from the transected tendon ends were collected on days 10, 15, and 20 postoperatively. While a traction force of 0.00245 N was applied to these specimens, the process of tendon gel changing into a tendon was video recorded for 24 h, and the length of extension was measured over time. Regenerated tendons were stained with hematoxylin and eosin for histological examination. Healing site was studied histologically according to the our maturity score with reference to the Bonar’s scale.ResultsThe day 10 specimens gradually stretched for 12 h after the start of pulling and transformed into tendons. In contrast, the day 15 and 20 specimens stretched immediately after the start of pulling and transformed into tendons. The day 10 specimens stretched significantly more than the day 15 and 20 specimens (mechanical strain; 0.43 ± 0.26%, 0.03 ± 0.02%, and 0.03 ± 0.01%, respectively)Statistically significant differences were observed in the day 10 specimens than in the day 15 and 20 specimens. (P < 0.017). Using our maturity scores, the day 15 and 20 specimens were more mature than the day 10 specimens. (1.6 ± 0.68, 3.9 ± 0.54, and 4.8 ± 0.64, respectively) Statistically significant differences were observed in the day 10 specimens than in the day 15 and 20 specimens (P < 0.017).ConclusionTendon gel physiologically and histologically matures on or after day 15 and becomes stronger dynamically in mechanical strength after day 15 than after day 10.

Investigating the histological and structural properties of tendon gel as an artificial biomaterial using the film model method in rabbits

“…We attributed this result to the completion of the connecting junctions between the tendon parenchyma and tendon gel after the fth day in many tendon gels. Consequently, the contraction of the gastrocnemius exerted traction stress on the tendon gel, which was thought to promote morphological changes in the tenocytes and collagen maturation, as revealed by Torigoe et al [11] and Ohashi et al [13] using murine models.…”

“…Furthermore, tendons generally contain only a few at tenocytes [22,23], but in the gels of D3 and D5 observed in this study, many round cells-also considered tenocytes-were actually observed. According to the research by Ohashi et al [13] with murine models, tenocytes were generated at the edges of the tendon in the early stage; subsequently, they were spread throughout the gel and their shape was changed from round to at, indicating maturation. These ndings are similar to ours.…”

“…They also reported that a translucent gel-like substance-called tendon gelwas secreted from the cut tendon stump and it was a key material for tendon regeneration [11]; in addition, maturation of tendon gel induced by the application of mechanical stress was observed via electron microscopy [11]. Similarly, Ohashi et al [13] reported that tendon gel matures physiologically and histologically under traction; moreover, an appropriate in vivo preservation period is needed for optimal traction-induced tendon gel maturation in murine models. These results support other previous reports showing the importance of applying mechanical force for regeneration of injured tendons [14,15].…”

Investigating the histological and structural properties of tendon gel as an artificial biomaterial using the film model method in rabbits

“…However, D3 and D5 gels contained many round tenocytes. Ohashi et al reported that [ 23 ] tenocytes in the murine models were generated at the tendon edges during the early stage, spreading throughout the gel, and their shapes changed from round to flat, indicating in vivo maturation. We observed a histologically significant difference between D3/D5 and D10/D15 gels before the tensile process, which was because of the completion of connecting junctions between the tendon parenchyma and tendon gel.…”

“…They also reported that a translucent gel-like substance—called tendon gel —was secreted from the cut tendon stump and it was a key material for tendon regeneration [ 31 ]; in addition, maturation of tendon gel induced by the application of mechanical stress was observed via electron microscopy [ 31 ]. Similarly, Ohashi et al [ 23 ] reported that tendon gel matures physiologically and histologically under traction; moreover, an appropriate in vivo preservation period is needed for optimal traction-induced tendon gel maturation in murine models. These results support other previous reports showing the importance of applying mechanical force for the regeneration of injured tendons [ 12 , 34 ].…”