In 2004, when American scientists first used stem cells in the skin of mice to grow hair follicles, Jay Leno, host of the famous US talk show “Tonight Show”, joked that scientists had “cured baldness… At least in mice.” Sixteen years later, a new study in the academic journal Nature is finally taking an important step towards “curing” human baldness.
(Original title: Harvard scientists grow artificial skin to grow hair, casting a cure for “vultures”)
Journalist Zhang Wei
On June 3rd, local time, Harvard Medical School and others in the academic journal Nature, the new breakthrough in the field of artificial skin , the use of human polyenergy stem cells to grow hair-growing skin-like organs.
Nature specifically invited Dr. Leo L. Wang, Department of Dermatology, University of Pennsylvania School of Medicine, and Professor George Cotsarelis, Director of Dermatology, to write a news and opinion piece on the results.
The pair commented that the results brought people “one step closer to producing an unlimited amount of hair follicles” that could be “transplanted to the scalp of a hair-thinning or hairless person.” “Furthermore, if this method is applied clinically, those with wounds, scars and hereditary skin diseases will have the opportunity to receive revolutionary treatments.” “
George Cotsares told Newsbeat (www.thepaper.cn) that he believes the paper is an important step in addressing hair loss and hair transplantation.
“The authors demonstrate that organ-like organs (artificial skin) can be transplanted into immunodeficiency mice and grow hair. This suggests that they can eventually be transplanted into the human scalp. “Immune-deficiency mice are used to ensure that the graft is not rejected by the immune system of the mice.
d. Naked mice with inadequate immune function received skin organ transplants 38 days later. Coloring hair (dashed box) is visible at both porting sites. One of the transplant sites (right, asterisk) has 14 hair follicles. Skin organ culture lasted 178 days.
Mouse back son out of human hair
Scientists’ research into skin tissue engineering began in 1975. At the time, a landmark study found that keratosis-forming cells can be isolated from the skin’s surface and cultured in vitro. About 10 years later, horny-forming cells isolated from burn patients began to be used for skin transplants to save lives.
To further the skin tissue engineering, the transplanted skin must contain more parts of the normal skin, such as hair follicles, melanocytes, sweat glands, nerves, muscles, fats, immune cells, and epidermal cells.
The above-mentioned research by Harvard Medical School and other institutions focuses on this.
Karl Koehler, an assistant professor of otolaryngology at Harvard Medical School, Jiyoon Lee, a research assistant, and colleagues reported that organ culture systems, after carefully optimizing growth conditions, were able to use human multi-energy stem cells to produce skin-like organs.
In vitro skin culture process
After 4-5 months of culture using human polysaccocells, they formed layers of skin tissue that contained hair follicles, sebum glands and neural circuits. When it was transplanted to the skin on the back of an immunocompromised mouse, 55 percent of the grafts grew 2-5 mm of hair. This suggests that the organ can be fused with the mouse epidermis to form skin containing human hair.
The authors found that their organs had the characteristics of chin, cheek and ear skin in gene expression. Other indications are that these organs may actually mimic scalp skin, and by altering the culture conditions of cell growth, skin with different body parts can be customized.
70 days into the birth stage
The skin is a complex multi-layered organ that participates in various processes such as body temperature regulation, body fluid maintenance, tactile and pain perception. Rebuilding the skin and its associated structure is one of the major challenges in the biomedical community for a long time.
In general, Cotsares says, in vitro production of tissue is quite challenging because cells do not grow in a normal environment. “Hair and skin are formed in the right three-dimensional environment through the process of coordinating signaling molecules. It’s challenging to do this manually, but the authors were able to simulate many of these processes in their organ-like organs. “
The paper introduces the culture process of skin organs in detail. Karl Koehler and colleagues added growth factors to stem cells, using inhibitors of bone-form protein 4 (BMP4) and conversion growth factor-beta (TGF-beta) to induce epidermal formation. Next, they applied the cells inhibitors of the growth factor FGF2 and bone-form protein (BMP) to induce the formation of cranial nerve cells, which produced dermis.
Cells are placed to grow in a sphere. After more than 70 days, the hair follicles begin to appear and eventually produce hair. Most of these hairs are dyed by melanin cells, which are also developed by cranial nerve cells. Subsequently, the sebum glands, nerves and their receptors, muscles and adipose tissue associated with the hair follicles begin to form, resulting in a very complete skin.
Growth efficiency and other issues to be solved
Research by Karl Koehler et al. demonstrates the potential of artificial skin for wound healing, scarring and hair transplantation. But Leo L. Wang believes that the study still has several problems to solve before it can actually be applied to the clinic.
For example, how efficient and repetitive is hair growth? If used for transplantation, how many cells are needed to eventually form the hair follicles?
Cotsares told Newsbeat that the artificial skin lacks immune cells, and there is no evidence that the hairites it grows can grow in a human hair cycle.
He also noted that in laboratory studies, artificial skin needs to be prepared for 140 days before implanting mice, which may hinder its therapeutic potential. In reality, skin transplants in burn patients can’t wait so long.
“Despite these statements, Lee’s research and colleagues are an important step towards ‘curing’ human baldness and paving the way for other and greater possibilities for treatment.” “This work has great clinical potential, and we believe that this hope will eventually become a reality. “