Effect Of Tacrolimus On The Growth Cycle Of Murine Hair Follicles,Human Hair Follicle And Hair Papilla Cells In Vitro

Tacrolimus, belonging to macrolides, is a widely usedimmunosupressive agent to patients who received liver transplantation orrenal transplantation. It can inhibit the activation of T lymphocyte andaccrementition of B lymphocyte which relys on T accessory cell. Also, itcan suppress the expression of interleukin-2, interleukin-3, interferon-γand interleukin-2 receptor. Recent researches found that Tacrolimus couldpromote hair growth. Ward found that the systemic use of Tacrolimuscaused the patient's eyelashes thicker and longer. Yamamoto showed thatthe application of Tacrolimus externally stimulated hair growth of miceand hamster. This effect of hair growth stimulating was remained to the16th day. Wu xianjie reported Tacrolimus would promote the growth ofmice's bristle hair follicle with the concentration ranging from 0.003mg/Lto 0.3mg/L. But up to date, the possible mechanism is still not clear.A unique feature of the hair follicle is its cyclical behavior. Thedermal papilla is necessary to both induce and maintain of hair follicle.The volume of the dermal papilla, which is determined by the number ofmatrix cells in the hair bulb, determines the diameter of the induced hairshaft and may also determine the duration of anagen. As it is known, dermal papilla produces many kinds of growth factors and cytokines,including insulin-like growth factor (IGF)-1, basic fibroblast growthfactor (bFGF), hepatocyte growth factor (HGF), vascular endothelialgrowth factor (VEGF), tumour necrosis factor (TNF)-2, interleukin (IL)-1and IL-6. Recently, the studies showed that VEGF played an importantrole in hair cycle and hair growth, which could be blocked by VEGFneutralizing antibodies. These results confirmed that VEGF was anautocrine growth factor of hair dermal papilla cells. It was assumed thatVEGF regulated hair cycle and hair growth by two following possiblemechanisms. The first, VEGF stimulated dermal papilla cell proliferationand migration. The second, VEGF induced perifollicular vascularizationin anagen. Recently HGF had been identified as a powerful modulator ofhair growth and may play an important role in hair follicle developmentand cycling. Dermal papilla cells cultured in vitro could autocrine HGFwhich further stimulated the synthesis of cell DNA and made the hairshaft grow longer. The mouse hair follicles where the skin received HGFinjection could retained in the anagen for 10 days, which suggested thatHGF delayed the transition from anagen to catagen. It had been foundthat the expression of VEGF and HGF in hair follicle was significantlyhigher in anagen and became weaker or disappear in catagen and telogen.So they play an important role in hair cycle.This paper can be divided into three parts: PartⅠ: Using C57BL/6 mice as model of hair follicle cycle toinvestigate how tacrolimus effect on mouse hair follicle cycle and find itspossible mechanism.All hair follicles of C57BL/6 mice in 6～8 weeks are during telogenif they are feeded well. Moreover, they would not go into anagenspontaneously under nomal condition. After artificial depilation, hairfollicles of mice in 6～8 weeks can be induced into anagen, catagen,telogen in order, just like the natural hair follicle cycle. The skinmelanocytes are only resident in hair follicle, and it synthetizes melaninand transfers melanin to the Malpighian cell only in anagen. So inanangen the skin is black. In catagen, the melanin becomes less, so theskin is grey. The skin becomes pink because of the complete stop ofmelanin synthesis. So we can simply judge the hair cycle according to themice skin colour. Chase indicated that the anagen of C57BL/6 mice couldremain 17～19 days, which could be divided into 6 deuto-stage based onmorphology. The catagen was very short, in which the hair papilla grewsmaller and the inferior segment of the hair follicle degenerated, whichmade a epithelium rope with the hair papilla. After that, this rope shrinksand the hair papilla go up to the arrector muscles of hair. The hairfollicles go into the telogen.We used the C57BL/6 mouse model to study how tacrolimus effectthe mouse hair follicle cycle. The animals were divided into three groups: tacrolimus group, vaseline group and minoxidil group randomly. On thefifth day after depilation, the hair follicle of the tacrolimus group and theminoxidil group mice were during anagenⅤ, while the hair follicle of thevaseline group was during anagenⅢ. On the fifth day after depilation,VEGF (vascular endothelial growth factor) mRNA and HGF (hepatocytegrowth factor) mRNA could be detected in the skin of the tacrolimusgroup and the minoxidil group, but they could not be found in the skin ofthe vaseline group. These results indicated that tacrolimus can promotethe murine hair follicle to enter the anagenⅤin advance, perhaps thispromotion was related to VEGF and HGF.PartⅡ: Effect of tacrolimus on the human hair follicles and humanDPCs in vitro.The study is about how tacrolimus affect human follicles in vitro, theThe scalp was sterilized and cut between the derma and subcutis, thenhair follicles were isolated with a forceps. The anangen hair follicles wereselected. The hair follicles were incubated with 0.001mg/L, 0.003 mg/L,0.006 mg/L, 0.01 mg/L, 0.03 mg/L, 0.06 mg/L tacrolimus, 2% minoxidiland simple williams E medium. Hair follicles supplemented with0.001～0.003mg/L tacrolimus grew significantly faster than those in thecontrol group (P＜0.05).PartⅢ: The effect of tacrolimus on human DPCs in vitro.The study is about how tacrolimus affect DPCs in vitro. Human dermal papilla cells (DPCs) were incubated with tacrolimus in ninedifferent concentrations for 72 h, then the cell proliferation was detectedusing MTT assay. The result showed that 0.0001～0.0003mg/L tacrolimuspromoted the cell proliferation significantly (P＜0.05).