Lentiviral-based BMP4 in vivo gene transfer strategy increases pull-out tensile strength without an improvement in the osteointegration of the tendon graft in a rat model of biceps tenodesis

✍ Scribed by Michael J. Coen; Shin-Tai Chen; Charles H. Rundle; Jon E. Wergedal; Kin-Hing William Lau

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 530 KB
• Volume: 13
• Category: Article
• ISSN: 1099-498X
• DOI: 10.1002/jgm.1604

✦ Synopsis

Abstract

Background

The present study aimed to develop a rat model of biceps tenodesis and to assess the feasibility of a lentiviral (LV)‐based bone morphogenetic protein (BMP) 4 in vivo gene transfer strategy for healing of biceps tenodesis.

Methods

A rat model of biceps tenodesis was developed with an interference‐fit open surgical technique. A LV vector expressing a BMP4 gene or β‐galactosidase (β‐gal) control gene was applied to the bone tunnel and the tendon graft before its insertion into the bone tunnel. Osteointegration was assessed by histology and pull‐out tensile strength was measured by a biomechanical test suitable for small rat biceps tendon grafts.

Results

Neo‐chondrogenesis was seen at the tendon–bone interface of LV‐BMP4‐treated but not control rats. The LV‐BMP4‐treated rats showed 32% (p < 0.05) more newly‐formed trabecular bone at the tendon–bone junction than the LV‐β‐gal‐treated controls after 3 weeks. However, the sites of neo‐chondrogenesis and new bone formation in the LV‐BMP4‐treated tenodesis were highly spotty. Although the LV‐BMP4 strategy did not promote bony integration of the tendon graft, it yielded a 29.5 ± 11.8% (p = 0.066) increase in improvement the pull‐out strength of rat biceps tendons compared to the LV‐β‐gal treatment after 5 weeks.

Conclusions

Although the LV‐BMP4 in vivo gene transfer strategy did not enhance osteointegration of the tendon graft, it yielded a marked improvement in the return of the pull‐out strength of the tendon graft. This presumably was largely a result of the bone formation effect of BMP4 that traps or anchors the tendon graft onto the bony tunnel. Published 2011. This article is a US Government work and is in the public domain in the USA.