A culture refers to culturing of any kind of cells or growth of cells on a suitable nutrient medium under in vitro conditions. A cell culture initiated to formation of tissues can be termed as tissue culture. It is basically of two types:
(i) Cell culture: where the tissues which are cultured are broken down into cells by enzymatic or mechanical means.
(ii) Organ culture: where the tissue culture are further developed into maintaining their structure and resulting in production of specific organs.
Isolation of animal cells and establishment of its successful cell culture leads to formation of primary culture. This when sub cultured produces cell lines. Cell lines which dies after several subcultures is known as finite and those which survive multiple subcultures and continue to grow indefinitely is known as continuous cell line.
Culturing of animal cells under invitro conditions leading to production of organs or parts of organs such that, they retain or closely exhibits their structure and functions is known as organ culture.
Human skin is the largest organ of the human body giving structure to the body and serving as the first line of defense of the body against infections. It is basically formed of two layers: the outer or epidermal and inner or dermal layer.
Advances in the field of biotechnology, research and medicine has made it possible to produce artificial skin in vitro. The first successful result in this field was accomplished in around 1970s by two scientists named Burke and Yannas. The synthetic skin they produced was termed as Silastic. The Silastic so produced was successful in producing only the epidermal layer of skin and could not, however, develop the dermal layer.
Living skin equivalent (LSE):
A further development led to production of structure called living skin equivalent which essentially resembles complete skin (epidermis as well as dermis).This is also known as graftskin.
The corresponding procedure involves isolation of living skin explants either from the required patients or from the newborn infants; culture and growth of such explants in a collagen matrix.
The skin at large is made up of cells known as keratinocytes. These cells produce dead cells or corneocytes which make up the outermost layer of skin. The keratinocytes during their transition to corneocytes expel lipid molecules. These dead cells along with lipid molecules together form the living skin equivalent under invitro conditions. The explant isolated consists of keratinocytes extensively. This undergoes trypsin treatment in order to break down the tissue into cells. Studies have revealed that irradiated 3T3 fibroblasts, which is a continuous and non tumorigenic cell line, promotes keratinocyte growth and proliferation. Thus, following the trypsin treatment the cells are cultured in 3T3 lined vessels. The proliferation result in the formation of colonies of cells which is again subjected to dissociation into individual cells. After a number of cultures and subcultures, a pure multilayered sheet of epithelium called cultured epidermal sheets (CES) is achieved. These sheets produced are then detached from culture vessels, cleaned and then applied for grafting. For the complete success of the procedure, it is important that the living explants are isolated from the respective patient so as to defer the possibility of rejection by the patient’s immune system.
(i) Treatment of burns: - The most important application in developing a living skin equivalent is in the treatment of people suffering severe burns. Often in such cases when grafted with the patient’s own skin taken from elsewhere in the body, it does not regenerate rapidly to cure the burns effectively. Similarly, xenografting can induce severe rejection reaction from the body. But the graftskin technology has proved successfully to aid in such treatment to larger extent so much so that, majority of the fundamental skin components were regenerated. This is also of great importance to people affected with skin cancer wherein such graft skin can be used for developing non cancerous cells and thus aid in cancer treatment.
(ii) Wound healing: - Another vital role of graftskin is in healing of wounds produced on skin by various diseased conditions. Thus, chronic skin ulcers (eg: foot ulcers developed as a result of diabetes) can be treated with living skin equivalent.
(iii) Providing model environment for research: - Since the graftskin produced resemble the living skin extensively, it can be employed as a medium to carry out various skin related research.Variations in the medium used for developing the related tissue has been introduced such as, introduction of fibroblasts for better differentiation and vitamin c for improved barrier functions of differentiating cells. Diseased skin condition can also be induced under invitro conditions in such living skin equivalents so that they can be studied closely into developing probable cure.
(iv) Testing dermatological products: - Artificial skin can also be used to test the effectiveness of various dermatological products rather than testing on the lab animals.
Thus it can be concluded that the living skin equivalent or artificial skin exhibits a wide range of future prospects having clinical, laboratorial and medical applications.