[Impact of TGF-beta1 antisense on collagen-binding integrins in keloid]

Focal adhesion kinase (FAK) siRNA inhibits human hypertrophic scar by suppressing integrin α, TGF-β and α-SMA

The effect of focal adhesion kinase (FAK) on suppressing scarring and the potential molecular mechanism underlying it has been investigated. Ten samples of human hypertrophic scars (HS) tissue cultured in vitro were transfected with FAK siRNA mediated by liposome. Quantitative real-time PCR was used to detect the expression of integrin α, transforming growth factor-β (TGF-β), FAK and α-smooth muscle actin (α-SMA) after transfection. MTT assay was used as a measure of fibroblast proliferation. Flow cytometry and (3)H-proincorporation technique gave measurements of the cell cycle and the quantity of collagen synthesis, respectively. Expression of FAK was effectively blocked, accompanied by decreasing expression of integrin α, TGF-β and α-SMA in hypertrophic scars fibroblast (HSFB) cells. One to 4 h after transfection with FAK siRNA, proliferation of HSFB cells was strongly inhibited (P < 0.01), reaching a maximum at 48 h. The proportion of G1 cells was higher and the proportion of the S and G2 cells lower after transfection. The amount of collagen synthesis in HSFB cells decreased when HSFB cells were transfected for 48 h. RNA interference targeting the FAK gene can block the two abnormal signal transduction pathways mediated by the integrin and TGF-β receptors that are responsible for hyperplasia and contracture of the scar, making FAK iRNA therapy a potentially effective approach in HS treatment.

Update on Keloid Management: Clinical and Basic Science Advances

BACKGROUND

Keloids are benign, fibroproliferative lesions that represent abnormal healing resulting in excessive fibrosis. They are composed of mainly type III (early) or type I (late) collagen. Some of the symptoms include pruritus, tenderness, and pain. Often, they are very difficult to treat and prevent from recurrence. In contrast to hypertrophic scars, keloids extend beyond the margin of the wound.

THE PROBLEM

There is very limited evidence on the best wound management for minimizing scarring. Multiple available therapeutic modalities have been used for the treatment of keloids; however, high-recurrence rates continue to be reported. Unsuccessful treatment of keloids leads to psychological impact on the patients and increased economic burden.

BASIC/CLINICAL SCIENCE ADVANCES

Currently, there are biological and antineoplastic agents that can potentially treat and prevent excessive scar formation. Some of them have been used as "off label" therapies, and others are still in the experimental phase such as interferon alpha (IFN-α), imiquimod, and transforming growth factor beta1 (TGF-β1). The use of IFN-α2b showed 18% recurrence rate when applied to postsurgical excised keloids. Imiquimod 5% can lower recurrence rate on postshaved keloids to 37.5% at 6-month and to 0% at a 12-month follow-up period. TGF-β1 oligonucleotides have shown effective and long-lasting inhibition of TGF-β-mediated scarring in vitro as well as in animal models. Daily injections of neutralizing antibodies against TGF-β1 and -β2 have shown successful reductions in scarring.

CONCLUSION

Latest discoveries in the use of novel agents suggest therapeutic alternatives for the prevention of recurrences of hypertrophic scars and postexcision keloid lesions.