| Research backgroundWith the development of communication technology, contact between people is becoming more frequent day by day. To get more chances at study and at work, people begin to spend more energy on modeling a good appearance. As a result, the subjects aiming to model good appearance raised up. In daily communication, the facial features are the most important composition of the first impression. The hair, is the key of the key. Many kinds of product which are used to protect hair were put into the market, bringing large economic effects.Hair follicle covers the surface of mammals. It is a kind of appendage of mammals’skin. It is composed of the epithelial components and the dermal components. The epithelial components include the out root sheath, the inner root sheath, the hair matrix and the hair shaft. The dermal components include the dermal papilla and the dermal sheath. The interaction between the epithelial components and the dermal components run through the overall process of the development and cyclical growth of the hair follicle. Once the interaction between the epithelial components and the dermal components was disturbed, the shape of the hair follicle would change, thus affecting the appearance of the people. Clinically, this kind of effect is characterized by various kinds of alopecia. For example, some kinds of chemotherapeutic can rapidly convert the hair follicle from anagen to catagen and telogen, causing the dropping of the hair follicles. Endocrine hormones such as androgen, can microminiaturize the hair follicle, causing ingravescent alopecia.Alopecia caused by many kinds of reasons brings much inconvenience to people’s social life. At present, there are two primary kinds of clinical treatment for alopecia, one is the pharmacotherapy, the other is operative therapy. In clinical, the primary medicines used to treat alopecia are Propecia finasteride and Regaine minoxidil. Propecia finasteride keeps testosterone from turning into dihydrotestosterone, thus keeping the hair follicle from microminiaturization. The hairs can be thicken and elongated again, so the symptom of alopecia can be improved. Regaine minoxidil promotes the secretion of the VEGF of the dermal papilla cells, thus enhancing the hair induction capacity of the dermal papilla cells and promoting the growth of the hair follicle. However, even though the pharmacotherapy can remit the symptom of alopecia over a period of time, once the pharmacy was ceased, the symptom of alopecia would recur. Besides, long-term pharmacotherapy would cause evident side effect. At the same time, pharmacotherapy would not be effective to everyone. To solve these problems, operative therapy is getting more and more popular.The highest density of hairs which the human’s eye can distinguish is about30hairs per square centimeter, this number is lower than the normal density of human’s hairs. That means it is theoretically feasible to conceal the alopecia areas by reasonably redistributing the hairs, without bringing a more sparse appearance of hairs of the donor site. Before1960s, because of the restriction of technology, doctors could redistribute the hairs only by expanding the scalp tissue and transferring skin flap. This kind of method is not only hard for a precise reduction of the alopecia area, but also highly invasive. After1960s, with the development of the microsurgical technique and the presentation of the conception of the follicle unit, the redistributing of hairs could be accomplished by the microscopy transplantation of the follicle units. By means of biopsying scalp to isolate follicle units or directly extracting follicle units from the donor site with drill, a mass of follicle units can be harvested. When the follicle units are reasonably transplanted into the recipient area, the alopecia area will get follicle unit with an appropriate number and an appropriate type. In terms of the choice of the donor site, the donor dominant theory considers that a hair follicle would maintain its intrinsic properties when it was transplanted into the recipient area. That made the occiput the best donor site. Because the hair follicles in the occiput are hardly affected by miniaturization, when they are transplanted into the recipient site, they will not be miniaturized. Besides, the scar in the occipital donor site will not be obvious because of the cover of surrounding hairs. However, the application of the follicle unit transplantation is restricted by insufficient donor site. After all, the follicle unit transplantation can’t increase the number of the hairs, it only redistributes the existing hair follicles. To increase the number of the hairs, hair follicle tissue engineering raised up.Hair follicle tissue engineering is aiming to reconstruct hair follicles. The microenvironment needed for the development of the hair follicle is complicated, it is hard to simulate it in vitro at present. As a result, there is not any mature hair follicle which is reconstructed in vitro at present. To the hair reconstruction in vivo, however, a lot of achievements have been made. Many kinds of animal models have been successfully constructed. The chamber model, the patch model, the flap model and the sandwich model are the most common animal models. Different animal models have different advantages and different disadvantages. Among all the animal models, the chamber model has the characteristics that the hairs reconstructed have the same orientation and the hairs can be directly observed on the body surface of the animal. With the help of the animal models, people began to research the conditions on which the hair induction capacity of cells would change, aiming to find the cells that could proliferate constantly and maintain a strong capacity of hair induction at the same time, create condition for the reconstruction of hair follicles with integrated structure and normal function in vitro. It was discovered that the hair, induction capacity of the cells would change when the cells had been cultured in vitro. When adding some kinds of biological activities to the cells which had partly lost their hair induction capacity, the hair induction capacity of the cells could be enhanced. Usually, the biological activities were added to dermal papilla cells, leading a stronger capacity of the dermal papilla cells to form dermal papilla. The aggregation of the dermal cells is the base of the development of the hair follicle. The signal activates the development of the hair follicle is called the First Dermal Signal, this kind of signal distributes extensively in the dermis of the embryo. Embryonic dermal cells secrete this kind of signal and some of the cells themselves are target cells of the signal at the same time, they receive the stimulation of the signal and aggregate to form dermal aggregation, initiating the development of the hair follicle. To investigate the effects of this kind of embryonic cells on the adult cells, we conducted our research. Because the First Dermal Signal distributes extensively in the dermis of the embryo and reaches its peak at embryonic day14, our research took the embryonic mice dermal cells of embryonic day14as the signal source to investigate its effects on the hair induction capacity of the mice dermal cells. We evaluated the hair induction capacity of the cells by calculating the number of the reconstructed hairs. For a efficient calculation of the number of the reconstructed hairs, we chose the chamber model, because the hairs reconstructed in the chamber model are located on the body surface and of the same orientation, which is convenient for harvesting and calculating. Our research was divided into two sections.1. Construction of the chamber model and the evaluation of the hair induction capacity of the cellsObjectives:to determine whether the chamber model is fit for harvesting the reconstructed hairs and calculating the number of the reconstructed hairs, whether the chamber model is fit for reflecting the hair induction capacity of the cells. Meanwhile, observe the intensity of hair induction capacity of different cells, get ready for the next experiment.Method:1. Got reagent bottle plug made of medical polypropylene, punched at the bottom of it to make a chamber.2. Executed newborn C57BL/6mice, used its back skin to prepare suspension of newborn mice dermal cells and newborn mice epidermal cells respectively, labeled the newborn mice dermal cells with Dil.3. Cultured the newborn mice dermal cells and prepare suspension, labeled the cultured newborn mice dermal cells with Dil.4. Prepared the suspension of embryonic mice dermal cells of embryonic day14, labeled the embryonic mice dermal cells with Dil.5. Cut out round piece of back skin of the nude mice, input the chamber, added cells into the chamber from the hole on the chamber according to the grouping.6. Set the following6groups:freshly isolated neonatal mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107), Cultured neonatal mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107), embryonic mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107), freshly isolated neonatal mice dermal cells(1×107), freshly isolated neonatal mice epidermal cells(1×107), embryonic mice dermal cells(1×107). Observed the results of hair reconstruction of these groups.Results:The group of freshly isolated neonatal mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107) reconstructed a lot of hairs. The group of cultured neonatal mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107)reconstructed a few hairs. The group of embryonic mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107)did not reconstruct any hair. The group of freshly isolated neonatal mice dermal cells(1×107)did not reconstruct any hair. The group of freshly isolated neonatal mice epidermal cells(1×107)did not reconstruct any hair. The group of embryonic mice dermal cells(1×107)did not reconstruct any hair. The difference of hair number between the group of freshly isolated neonatal mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107) and the group of cultured neonatal mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107)was of statistical significance(n=3, t=14.85,p<0.05). When the tissue with hair follicles was sectioned and put under the fluorescence microscope, all the dermal papilla could be judged as Dil p<ositive. The reconstructed hairs were in alignment, they were of not obvious difference with normal back hair of C57BL/6mice, they could also subsist in normal hair cycle.Conclusions:1.chamber constructed with the medical polypropylene is fit for reconstructing orderly hairs, harvesting the reconstructed hairs and calculating the number of the hairs. With this kind of chamber model we can compare the hair induction capacity of different cells.2. The reconstruction of hair follicle depends on the interaction of the epithelia cells and the dermal cells, none is dispensable.3. The hair induction capacity of the freshly isolated neonatal mice dermal cells would recede if they were cultured in vitro.4. Embryonic mice dermal cells of embryonic day14can’t interact with freshly isolated neonatal mice epidermal cells to form hair follicle.2. Hair reconstruction with cultured neonatal mice dermal cells with the aid of the embryonic mice dermal cellsObjectives:To observe the effects of the embryonic mice dermal cells on the hair induction capacity of the cultured neonatal mice dermal cells, and investigate the mechanism.Method:Reconstructed hair follicle with cultured neonatal mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107), added Dil-labeled embryonic mice dermal cells of embryonic day14(1×106)to build the experimental group, the control group was of no embryonic mice dermal cell of embryonic day14. Compared the number of the reconstructed hairs. Biopsied the hair follicle tissue of the experimental group to make histological observation.Results:The group of cultured neonatal mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107)+embryonic mice dermal cells(1×106)formed a lot of hairs, the group of cultured neonatal mice dermal cells(1×107)+freshly isolated neonatal mice epidermal cells(1×107)formed a few hairs. The difference was of statistical significance(n=3, t=6.75, p<0.05). All the Dil-positive cells located in the inter-follicle dermis. No Dil-positive dermal papilla was found.Conclusion:Embryonic mice dermal cells of embryonic day14can contribute to the hair follicle reconstruction system composed of cultured neonatal mice dermal cells and freshly isolated neonatal mice epidermal cells, in manner of enhancing the hair induction capacity of the cultured neonatal mice dermal cells. |
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