Differentially expressed proteins on postoperative 3 days healing in rabbit Achilles tendon rupture model after early...

Surgical repair of Achilles tendon (AT) rupture should immediately be followed by active tendon mobilization. The optimal time as to when the mobilization should begin is important yet controversial. Early kinesitherapy leads to reduced rehabilitation period. However, an insight into the detailed mechanism of this process has not been gained. Proteomic technique can be used to separate and purify the proteins by differential expression profile which is related to the function of different proteins, but research in the area of proteomic analysis of AT 3 days after repair has not been studied so far.

Forty-seven New Zealand white rabbits were randomized into 3 groups. Group A (immobilization group, n equal to 16) received postoperative cast immobilization; Group B (early motion group, n equal to 16) received early active motion treatments immediately following the repair of AT rupture from tenotomy. Another 15 rabbits served as control group (Group C). The AT samples were prepared 3 days following the microsurgery. The proteins were separated employing two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). PDQuest software version 8.0 was used to identify differentially expressed proteins, followed by peptide mass fingerprint (PMF) and tandem mass spectrum analysis, using the National Center for Biotechnology Information (NCBI) protein database retrieval and then for bioinformatics analysis.

A mean of 446.33, 436.33 and 462.67 protein spots on Achilles tendon samples of 13 rabbits in Group A, 14 rabbits in Group B and 13 rabbits in Group C were successfully detected in the 2D-PAGE. There were 40, 36 and 79 unique proteins in Groups A, B and C respectively. Some differentially expressed proteins were enzyme with the gel, matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). We successfully identified 9 and 11 different proteins in Groups A and B, such as GAPDH, phosphoglycerate kinase 1, pro-alpha-1 type 1 collagen, peroxiredoxin 1, alpha-1-antiproteinase E a-1 and MAD2L1 binding protein, etc. And some with the molecular chaperone, oxidative stress, energy metabolism, signal transduction, coupled with the tendon cell expression and protein synthesis, proliferate, differentiate and are closely related to the AT healing. The GAPDH protein was further validated through Western blotting. It was indicated that some differentially expressed proteins were involved in various metabolism pathways and may play an important role in initial healing of AT rupture.

Differentially expressed proteins in rabbit healing AT model may contribute to 3 days healing of AT rupture through a new mechanobiological mechanism due to the application of postoperative early kinesitherapy.