Effects of monofilament nylon coated with basic fibroblast growth factor on endogenous intrasynovial flexor tendon healing.
OBJECTIVE
We developed a monofilament nylon thread that can release various growth factors to enhance intrinsic reparative processes after flexor tendon injury. We evaluated the properties of this thread in vitro and in vivo.


METHODS
Nylon threads were coated with gelatin that subsequently was cross-linked in glutaraldehyde. The thread was soaked in basic fibroblast growth factor (bFGF) solution (400 microg/mL). Exogenous bFGF in the thread was released constantly over the course of 1 week. The biologic activity of bFGF and the biomechanical strength of the thread were examined in vitro and its efficacy was investigated in an in vivo rabbit tendon repair model after early flexion exercises. The sutured sites were examined histologically (hematoxylin-eosin, immunohistochemistry, in situ hybridization), biochemically (Western blot test), and biomechanically (ultimate load) after surgery.


RESULTS
This gelatin-coated thread absorbed iodine 125-labeled bFGF in a time-dependent manner. The total amount of bFGF absorbed by the thread within the tendon tissue was between 3 and 15 mug depending on the concentration of bFGF solution. Basic fibroblast growth factor protein was delivered selectively-not in the surrounding scar but in the repaired tendon-for 3 weeks. Histologic analysis showed that the cellular density at the repaired site increased in accordance with the expression of bFGF messenger RNA and protein in the tendon. Endogenous bFGF expression seemed to be enhanced transiently by exogenous bFGF during the first few weeks. The epitenon showed a vigorous fibroblastic response to the coated thread and the ultimate load also was increased significantly at 3 weeks after surgery.


CONCLUSIONS
This bFGF-coated nylon suture gave excellent results in delivering a drug selectively to tendon; it also induced an increase of biomechanical strength and a thickening of the epitenon layer in vivo during a 3-week period, thereby accelerating cellular proliferation, initially peripherally and later centrally. This system may become a therapeutic tool to be used in hand surgery.
Hamada
Yoshitaka
Y
Department of Orthopedics, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan. hamada-yoshitaka@umin.ac.jp
Katoh
Shinsuke
S
Hibino
Naohito
N
Kosaka
Hirohumi
H
Kosaka
Hirofumi
H
Hamada
Daisuke
D
Yasui
Natsuo
N
D000818:Animals; D049109:Cell Proliferation; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D005079:Excipients; D016222:Fibroblast Growth Factor 2 / Q000008:administration & dosage* / Q000032:analysis* / Q000096:biosynthesis; D005347:Fibroblasts / Q000378:metabolism; D005780:Gelatin; D066298:In Vitro Techniques; D008297:Male; D008422:Materials Testing; D023421:Models, Animal; D009757:Nylons / Q000737:chemistry; D011817:Rabbits; D013537:Sutures; D013708:Tendon Injuries / Q000601:surgery*; D013710:Tendons / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D013718:Tensile Strength; D014945:Wound Healing / Q000187:drug effects
D020099:Coated Materials, Biocompatible; D005079:Excipients; D009757:Nylons; D016222:Fibroblast Growth Factor 2; D005780:Gelatin