Effect of Basic Fibroblast Growth Factor in Perifascial Areolar Tissue Transplant

Abstract

Background Perifascial areolar tissue (PAT) transplant is a technique in which a sheet of connective tissue on the fascia is harvested and transplanted to the wound bed. PAT engraftment fails when the exposed area of tendons, bones, or artificial materials is large. On the other hand, combination of tissue transplant and basic fibroblast growth factor (bFGF) improves the survival rate of the transplanted tissue. Materials and Methods A wound model was created in which the artificial material was exposed on rats' backs. All the rats underwent PAT transplant, but the rats were divided into two groups according to the PAT processing method beforehand. In one group, the PAT was immersed in water for injection before transplant (bFGF[-] group), and in the other group, the PAT was immersed in bFGF product (bFGF[+] group). Specimens were collected 7 days after surgery to assess the histologic thickness of the PAT and the gene expression in the PAT. Results The thickness of the PAT in the tissue slices was significantly higher in the bFGF(+) group than in the bFGF(-) group. Expressions of CD34 and COL3A1 were significantly higher in the bFGF(+) group than in the bFGF(-) group. Conclusion The results of this study indicate that adding bFGF to the PAT transplant may promote PAT engraftment and wound healing by increasing angiogenesis and may increase granulation formation, which may result in a stronger covering that prevents the prosthesis from being exposed.

Keywords: basic fibroblast growth factor; loose connective tissue; perifascial areolar tissue; ulcer.

Fig. 1

( A ) A 20-mm-diameter skin was designed on the rat's back. ( B ) After the skin and panniculus carnosus muscle were removed, the perifascial areolar tissue (PAT) was marked over the latissimus dorsi muscle with a diameter of 20 mm. ( C ) The PAT to be harvested was pinched with forceps. ( D ) A silicon sheet with a diameter of 10 mm and a thickness of 0.5 mm was inserted on the fascia after the PAT had been harvested. ( E ) The silicon sheet was fixed by suturing it to the fascia at two places with 6–0 monofilament needle thread. ( F ) The harvested PAT was covered over the wound with a silicon sheet fixed. ( G ) A wound dressing was placed over the PAT and fixed with 5–0 monofilament needle thread around the perimeter.

Fig. 2

Perifascial areolar tissue (PAT) transplant model and schema of each group. In one group, the PAT was immersed in water for injection before transplant (bFGF[–] group, n  = 3), and in the other group, the PAT was immersed in bFGF product for 5 minutes (bFGF[+] group, n  = 3).

Fig. 3

( A ) Seven days after surgery, the rats were euthanized under carbon dioxide inhalation and the wound dressing was removed. The left-sided tissue divided at the midsagittal section was used for histologic examination, and the right-sided tissue immediately above the perifascial areolar tissue (PAT) was used for gene expression analysis. ( B ) The thickness of the PAT was measured as the average value of the three set sites. The thickness of the three-set site was the thickness of the tissue at the vertical lines drawn from the center and the left and right 1/4 points of the reference line drawn horizontally on the existing silicon portion. The length of the straight yellow line is the thickness of the PAT. PCR, polymerase chain reaction. ( C ) Macroscopic findings of tissue after formalin fixation. The location of silicon insertion is indicated.

Fig. 4

( A ) Wounds of rats in the bFGF(–) group. Silicon was visible in the deep layer of the thin perifascial areolar tissue. ( B ) Wounds of rats in the bFGF(+) group. Firm granulation has formed. ( C ) Macroscopic finding of the bFGF(–) group. The tissue on the silicon is extremely thin. ( D ) Macroscopic finding of the bFGF(+) group. The silicon is covered with a thick tissue. ( E ) Histologic finding of the bFGF(–) group. Connective tissue that stained blue with Masson trichrome staining is observed. ( F ) Histologic finding of the bFGF(+) group. A thick layer of connective tissue is observed over the space of the silicon sheet.

Fig. 5

( A ) Evaluation of perifascial areolar tissue (PAT) thickness. The thickness of the PAT in tissue sections was significantly higher in the bFGF(+) group (2.37 ± 0.81 mm) than in the bFGF(–) group (0.81 ± 0.54 mm; p  = 0.05). ( B ) CD34 expression was significantly higher in the bFGF(+) group (GE: 6.28 ± 3.29) than in the bFGF(–) group (GE: 1.81 ± 1.85; p  = 0.05). ( C ) Expression of COL3A1 was also significantly higher in the bFGF(+) group (GE: 97.2 ± 73.1) than in the bFGF(–) group (GE: 6.28 ± 3.29; p  = 0.04). ( D ) Regarding COL1A1 , the expression was higher in the bFGF(+) group (GE: 4.00 ± 2.03) than in the bFGF(–) group (GE: 1.85 ± 1.63), but not significantly so ( p  = 0.11).