| Hair initially grows over the scalp since the fetus,naturally becomes to be the scalp's first physical line as a kind of skin appendage.In daily life,it can not only resist the serious ultraviolet radiation of the summer sun and the bitter cold of the winter wind,but also contribute to the sweat evaporation of the head,protect the scalp in multiple ways.To be the most important,hair always plays a decisive role in the human body aesthetics.Lovely splendid thick black hair can bring a healthy and young impression,and thus develops one's self-confidence and charm in the social contact.Therefore,its psychosocial meaning is more significant than the original physiological meaning.However,with the quickened pace of life and increasingly fierce competition at workplace,alopecia becomes to be a common disease and attracts more and more people's attention.There are many reasons may take account for alopecia,such as androgenetic factor,congenital factor,mental factor,drug factor,physical-chemical factor,disorders of the endocrine-immune system and so on.Alopecia can be clinically divided into five types:androgenetic alopecia,hereditary alopecia,cicatricial alopecia,areata alopecia and acquired alopecia.The principal clinical methods of curing alopecia at present include surgical treatment,drug treatment,laser treatment,and some cosmetic techniques of covering bald area.However,follicular unit micro-grafting is the most common therapy and has the most significant effect among all of these treatments which have been used in clinic usually.Currently,besides hair restoration,it has been widely used for repairing and thickening the eyelash,eyebrow,beard,and even pubes as well.This technology can make follicular units redistributed through transplanting the single hair follicular unit which is harvested from the patient's occipital scalp into the bald area,thereby obtain more ideal postoperative appearance.But no matter which restoration technology can have a good expectation,the patient with sufficient hair follicular donor sites is the basic factor.The people who have insufficient donor sites or have a big bald area are disable to obtain an ideal postoperative result through surgical operation.In addition,alopecia commonly involves a progressive development,so hair restoration could not completely reverse or stop this process.Moreover,the expectation to predict or control long-term postoperative development can't come true.As a result,obtaining enough source of hair is in urgent need of solution at present.No matter study of hair follicle tissue engineering or hair follicle cell transplantation which is in the experimental phase,both of them couldn't be used in clinical treatment at current.To solve this problem,artificial hair comes to be available.The concept of artificial hair transplantation was proposed by Japanese scholar at first in 1976.Since it came out,it spreads all over the world and is widely welcomed.However,the fiber used before is mostly composed of polyacrylic acid,polyester fiber and man-made fiber which is got from the material that can resist the fire and chemicals.In addition,people use ethylene halide and acrylonitrile to make diaminoanisole which is a kind of cancerogen that can dye the man-made fiber.Therefore,almost all the grafts are fallen off in ten weeks.This is a kind of toxic and side effects brought by the cancerogen after transplantation.But because the operation is simple and not limited by the donor site,a more important advantage is its outstanding post-transplantation effect,many scholars are still devoting themselves to the perpetual research of the artificial hair.In 1996,an Italian scholar proposed a kind of polyamide artificial hair fiber named Biofiber that was permitted by European Union as a reparative medical supply.Foreign scholars used this material in the clinical experiment of alopecia restoration,and tracked its long-term follow-up.The result showed that its compatibility is good,and the postoperative adverse reactions are few and slight.It can be applied to the repair of a large area of alopecia.Nonetheless,polyamide artificial hair fiber could only one fiber in one hole that multiple fibers in one hole arise an increase in the frequency of adverse reactions,contributing to its density is 26.7 units per square centimeter,and the loss rate of this polyamide artificial hair fiber is 20%-30%per annum,the patients couldn't obtain a satisfactory effect despite retransplanting termly.As the result of the early animal experiment in our research group showed,the loss of the polyamide artificial hair fiber is mainly in the early phase after operation.This study intends to design a kind of transplantable wig composed of human hairs with a knot and a degradable base that can enhance the fixation of the wig in the early phase after transplantation.With degradation of the base,the surrounding tissue gradually grows into the loop and eventually encloses the hair.In addition,we design each transplantable wig contains one to four hair that can bring a more natural appearance than a single polyamide fiber.In this study,we manufactured the transplantable wig and tested its histocompatibility and long-term effects,explore its possibility as a new clinical treatment that may be available for alopecia restoration.Part One:Design and manufacture of transplantable wigsObjective:To explore a transplantable wig composed of degradable base which is similar to the structure of follicular unit and lay the foundation for the experimental animalsMethod:1.The designation of the transplantable wigs:the base of transplantable wig is lamellar,a knot was made in each hair tuft(containing 1-4 hairs)to form a loop(about 1 mm in diameter)and with a hole was made in the center.A barb containing the loop at an angle of approximately 30?45° between the barb and the base was shaped.Adjustment of the original hair length depends on personal requirements.2.The manufacture of transplantable wig:after the hair was soaked in 75%alcohol for 1 hour and 2%glutaraldehyde for 20 minutes,then rinsed with saline.A knot was made in each hair tuft(containing 1-4 hairs)to form a loop.PLGA was prepared using the heated-melt(120?±10°)method(placing it on a stainless steel plate and heating it on an electric furnace).The PLGA was removed when it reached the molten state.Then it was combined with the portion of the hair tuft containing the loop(about 1 mm in diameter).The softness of the PLGA at this point permitted blending by gentle pressure.After using another stainless steel press to compact them,the bundled hairs,tightly surrounded by PLGA,were demounted at room temperature.These lamellar semi-manufactures were pruned on the opposite side of loop along the longitudinal axis of the hair tuft.A barb containing the loop at an angle of approximately 30?45°between the barb and the base was shaped.Finally,the base was punched in the loop centrally.The base measured approximately 4.0 mm in length,1.5 mm in width,and 0.5 mm in thickness.3.Assessment of physical strength of transplantable wigs:the compactness between the base and hair was observed by scanning electron microscopy.Anti-tensile force assay was performed to estimate the stability of the transplantable wigs.Result:The human hairs were closely surrounded by the base,and there was no significant space in the contact area,as determined by the scanning electron microscope.Tensile-resistant force assay revealed that the connection of hairs and base was tight.The hairs could not be easily pulled out of the base,even though they were snapped.Conclusion:Owing to its good biocompatibility,PLGA has already been approved for widely biomedical applications.Combination of human hairs and PLGA were proceeded into a transplantable wig made the human hairs were closely surrounded by the base.The barb on the base may enhance the fixation of the wig in the early phase after transplantation.Moreover,each transplantable wig contains one to four hair that can bring a more natural appearance than a single polyamide fiber.The foundation for the experimental animals was laid.Part two:The degradation of PLGAObjective:To observe the degradation of PLGA in vivo.Method:Lamellar PLGA was made by extrusion molding,as described above,into 4.0 × 1.0 × 0.5 mm films.30 lamellar PLGA were implanted into 5 New Zealand rabbits' backs.At each point(1,2,4,6,8 weeks),one rabbit was selected at random,killed,and its dorsal implants were harvested.The retrieved PLGA films were soaked in collagenase solution and trypase solution to remove the integrated tissues,then dried in a vacuum drying oven to a constant weight.To observe the degradation of PLGA in vivo by the change of mass-loss ratio,molecular weight and morphology.Result:Through gross and microscopic observation,some small pores and gaps gradually appeared and became more and more visibly,contributing to a decreasing size.At the early stage after implantation of the PLGA film,its molecular weight was considerably reduced.However,the change of mass loss was nearly negligible during this period,the apparent change emerged until 6 weeks.On the contrary,the change of molecular weight was retarded after 4 weeks.At the end of 8 weeks,the films broke into micro fragments that were hardly visible.Conclusion:Owing to its good biocompatibility and controllable biodegradability through altering the ratio of two of its components,PLGA has already been approved for many biomedical applications.Part three:Histocompatibility and long-term effect after transplantation of the wigsObjective:Transplantation of the wigs into the rabbits' scalps to observe the histocompatibility and long-term effect after transplantation of the wigs,to explore the possibility of clinical application.Method:1.Transplantation in animals:36 New Zealand rabbits were divided into 3 groups at random(n=12).Transplantable wig(group A),polyamide fiber with a PLGA base(group B)and polyamide fiber(group C)were transplanted into the scalps of rabbits for 3 groups respectively and each rabbit was transplanted 40 units.Among these groups,group A was experimental group,group B and C were control groups.After transplantation,rabbits in each group were randomly divided into two groups,one for evaluation of histocompatibility and the other for observation long-term effect.2.Observation of histocompatibility:Scalp biopsies at the surgery sites were done 1,4,8,24,and 48 weeks after transplantation.The samples were undergone the hematoxylin and eosin(H&E)staining to observe any histological changes and the number of inflammatory cells around the hairpieces.3,Long-term effect after transplantation:Postoperative rabbit scalps were regularly observed.The loss rate of hairpieces in three groups were computed and compared at 1,4,8,24,and 48 weeks post-surgery.4.Statistical Data Analysis:All the data were expressed as mean ± SD,and a comparison of hairpiece loss rate was performed using One Way ANOVA Analyses with p-values<0.05 having statistical significance.Result:1.H&E staining of paraffin sections:The general inflammatory trend of the tissue surrounding the hairpieces was detected in three groups.Some inflammatory cells—mainly neutrophils and lymphocytes—were observed during the first post-operative week.After 4 weeks,fibroblastic proliferation and newborn capillaries emerged around hairpiece,the inflammatory cells decreased after 1 week,and a few multinuclear giant cells emerged.By 8 weeks,hairpieces were coated with increased fibroblasts and more compact fibrous tissue.As time went by,the proliferating fibroblasts had secreted more collagen fibers,and the inflammatory response lessened.No evidence of infection or necrosis had been identified by the 24th or 48th week after transplantation;hairpieces were encapsulated by collagen fibers while any inflammatory cells were hardly noted.2.Inflammatory cell numbers:The number of inflammatory cells was reduced continually over time in three groups.There was no significant difference between the three groups,except at 4 and 8 weeks,the less inflammatory cells was observed in group C(P<0.05).3.Long-term effect after transplantation:The slits on the scalp and the incisions on the back were initially slightly red and swollen,followed by full recovery 1 week later.Besides the desired direction and distribution achieved after transplantation,the wigs in the experimental group,each containing 1 to 4 hairs per tuft,had a more natural appearance,more like the follicular units than the control group(consisting of only a single fiber per tuft).A generally downward tendency of loss rate was seen in three groups.The total loss rate of 12.08±1.88%,12.5±1.58%and 20.42±1.88%at 48 weeks for the long term in group A,B,C,respectively.Group C had significantly lower loss rate(P<0.05).Conclusion:The design philosophy of the transplantable wig illustrated in our study was based upon follicular unit to make the transplant more natural and realistic in appearance than that of control group,which uses only one fiber per hole.The base did enhanced the fixing much more than polyamide fiber without the base,which significantly reduced the loss rate and laid good foundation for further clinical trial. |
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