Human Skin Structure: Epidermis, Dermis & Hypodermis - Essay Sample

Introduction

According to Stratton et al. (2016), the human skin consists of two primary layers comprising of packed epithelial cells, the dermis, epidermis, and hypodermis. The epidermis is the outermost layer of the skin while the dermis is the innermost layer. The epidermis contains a wide range of thickly packed cells, while the dermis consists of irregular and dense connective tissues. Underneath the dermis is the hypodermis comprising of loosely fatty connective tissues (Zhu et al., 2020). The aim of this paper is to provide a comprehensive literature review of different types of cells and cultures used in the production of skill layers.

Is your time best spent reading someone else’s essay? Get a 100% original essay FROM A CERTIFIED WRITER!

Save 25%

Discussion of the Epidermis, Dermis, and Hypodermis

According to Frueh et al. (2017), the epidermis comprises of the stratified squamous epithelium stacked in five layers. This part of the skin comprises of four remarkable layers, including the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum. However, the epidermis also contains the fifth layer located between the stratum granulosum and the stratum corneum. The entire section of the skin is vascular, which implies that it lacks blood vessels (Liu et al., 2013). All body parts have thin skin except the palm and the soled of the feet, which contain thick cells. Consequently, the dermis lies underneath the epidermis and comprises of sweat glands, hair follicles, and tough connecting tissues. This part of the skin has two primary layers that play a vital role in connecting collagenous and elastin fibers. Lastly, the hypodermis exists between the dermis and epidermis and connects the two skin layers to the muscles and bones (Kezic & Jakasa, 2016). Also, this skin layer consists of adipose tissue, areolar connective, and well-vascularized tissues.

Discussion of the Main Cells

Keratinocyte

Keratinocyte cells bear their location in the epidermis and help in the creation of tight regions of the skin nerves while maintain the Langerhans cells (Dhivya et al., 2015). These cells have four layers, including the stratum corneum, stratum granulosum, stratum spinosum, and stratum basale. Cell division and proliferation occur in the stratum basale layer within the keratinocytes. The stratum spinosum has 8 to 10 sheets of keratinocytes, while stratum granulosum has about 3 to 5 sheets and do not undergo division (Liu et al., 2013). Lastly, stratum corneum consists of 15 to 30 corneocytes sheets (Stratton et al., 2016). The keratinocytes serve as a barrier that prevents pathogens, heat, UV radiation, and water loss from the skin. These cells also play a critical role in signal transduction within the extracellular matrix (Kezic & Jakasa, 2016). Separation of keratinocyte cells can lead to cell amplification, which entails diverted movement towards the epidermis.

Basal Stem Cell

Basal stem cells are round-shaped group of cells found in the basal cell layer, which provides ample space for the creation of new cells through progressive division (Pereira et al., 2013). The new cells then force their way to the uppermost part of the skin for shading. Basal stem cells have junctions whose primary role is communication, attachment, and connecting with the extracellular matrix.

Fibroblast

The fibroblasts are a group of highly-elongated, flat, and large active cells (Liu et al., 2013). They extend outside of the cell body. Fibroblasts' cells are oval and flat. These cells produce tropocollagen, a gel occupying the cell spaces of the connective tissues (Stratton et al., 2016). Lastly, fibroblasts help in the process of wound healing.

Mesenchymal Stem Cells

Mesenchymal Stem Cells (MSCs) have unique immune-modulation functionality. These cells also have a self-renewal capability and a differentiation capacity (Pereira et al., 2013). Despite their differentiation and renewal characteristics, MSCs maintain their multipotency ability. Such cells are multipotent stromal and can differentiate, giving rise to marrow adipose tissues. After differentiating, they give rise to adipocytes, myocytes, and chondrocytes (Liu et al., 2013). MCS consist of thin and long cell structure. Typically, the cell body is covered by chromatin particles, around, and a large nucleus, having the appearance of a nucleus (El Agha et al., 2017). The other cell body parts comprise of polyribosomes, mitochondria, reticulum, rough endoplasmic and tiny Golgi bodies or apparatus, MSCs are widely spread, although devoid of fibris, the cells are populated within and around the extracellular matrix (Bhardwaj et al., 2015). MSCs apply in the treatment of disease. The engagement of the MSCs, especially in epithelial-mesenchymal alteration, forms a critical aspect of the cells (Klar et al., 2018). The majority of the MSCs can be mobilized and activated is required, although their efficiency in the clinical field remains low.

Developing Keratincyte From MSCs, Advantages, Disadvantages, and Differentiation

When MSC's are differentiated, they form keratinocytes. When MSC's detect KLK7, KLK6, and KLK5, especially on FRET peptides, they are differentiated into keratinocytes following a simultaneous morphological modification in addition to epidermal markets expressions that may include KRT14, KTR10, KRT5 and p63 (Hughes-Formella et al., 2019). Through inducement, MSC's are cultivated using EGF, together with 1.8mM calcium for approximately two weeks (Zhu et al., 2020). Between the days, p63 and KRT14 are observed. Till the end of the period, LKL activities are increased until the end of the process. The advantage of MSC differentiation is that it avoids the much-hyped ethical issues surrounding extensive research in embryonic stem cells. In the case of transplant, differentiation in MSC minimizes the risk of complications and dangers, especially in the allogeneic transplantation (Bhardwaj et al., 2015). Also, differentiation in MSC provides a wide range of cells critical in treating degenerative and acute illnesses. Lastly, numerous benefits come with differentiation that includes ease of growth, favorable immune ability, and play a significant role in regulating cells (Liu et al., 2013). However, differentiation is limited by the biphasic immunity in which the cells transits to an immune-privileged often linked to complexity in the antigen profile.

According to Mehrabanian and Nasr-Esfahani (2011), "hard" UCSC differentiates much easily as compared to "soft" ADSC. In most cases, ADSCs differentiate into three main lineages with considerable correlation identified. While adipogenesis correlated negatively, osteogenesis correlated positively. Therefore, the resulting mechanical characteristics show a precise prediction on how keratinocytes form. Identified changes in the mechanical traits indicate a high level of independence of the modifications realized in the resulting keratinocytes (Nicholas et al., 2016). The cytoplasmic and nuclear stiffness of the resulting keratinocytes showed significant similarity to UCSCs and ADSCs linkages. The development of keratinocytes arises from the differentiation of soft and hard MSCs (Mehrabanian & Nasr-Esfahani, 2011). This differentiation leads to the development of adipocytes and osteoblasts.

Skin Scaffolding Engineering Literature Review

Zhao et al. (2018) averred that the skin serves various essential purposes that include barrier against microbial infection, specific ultra-violet light, chemical factors, and numerous environmental factors. Other functions of the skin include maintaining appropriate moisture for biomolecules and underlying tissues. Skin severely damaged by bedsores, burns, trauma, and multiple diseases such as diabetes may not undertake their functionalities, a feat that may lead to amputation or death (Bhardwaj et al., 2015). It is, thus, critical to regenerate skin considered damaged or diseased by specific induction or engineering methods. Tissue engineering applies various materials known as scaffolds in supporting cell biochemical and seeding factors in the regeneration of their biological functionalities (Martinez-Perez et al., 2011). Scaffolding is one of the most used and promising methods.

Thermally-Induced Phase Separation

Akalin and Selamoglu (2019) defined thermally induced phase separation as a method in which dermatologists prepare polymer membrane by a substance acting as a solvent with polymer at high temperatures before casting the solution into a film. The cooling of the solvent leads to solidification (Pereira et al., 2013). The method plays a significant role in microcellular and microporous foam fabrication (Zou et al., 2018). Microporous membranes are used widely in kidney artificial, wastewater treatment, and removal of viruses. The technique provides critical support in the creation of new body tissues. The main disadvantage of thermally induced phase separation lies in the fact that it is costly to conduct because it relies solely on thermal energy (El Agha et al., 2017). Lastly, dermatologists can only achieve growth by adjusting the use of suitable morphology and process parameters, which are difficult to conduct.

Solvent Casting and Particulate Leaching

According to Cui et al. (2009), skin professionals use an organic solvent to dissolve a polymer in solvent casting and particulate leaching (SCPL). Consequently, the experts prepare a solution from the salt particles and the eventual mixture produced into a geometric shape. The resulting shape can produce any cast shape that creates a scaffold or three-dimensional molds. The scaffold provides a composite material made up of various particles after evaporation before setting it on a bath (Zhao et al., 2018). After dissolving, the end product produces a porous structure. The entire procedure is significant in generating a continuous and straightforward process used in the fabrication of porous scaffolds, especially in tissue engineering (Talukdar et al., 2014). The technology is also significant in mimicking the bone marrow niche. Dermatologists use SCPL to assess the effectiveness in novel healings, especially in clinical settings (Zou et al., 2018). SCPL is an innovative technique commonly used in the production of polymer built scaffolds and fabricates inventive 3D porous frameworks for the bone marrow and in multiple therapies (Hughes-Formella et al., 2019). The technique also provides an excellent thickness and elasticity in the use of soft tissue engineering.

Gas Foaming

According to Fregni et al. (2018), gas foaming emerged gradually as one of the most strategic fabrication techniques. The employment of the biopolymers leads to the production of excellent interconnected and porous scaffolds. This technique is significant in the development of sophisticated strategies that control scaffold microarchitecture (Squillaro et al., 2016). Also, gas foaming builds effective synthetic analogues that comprise of extracellular medium (Nardo et al., 2012). However, this technique has a limitation that involves a polydispersed aspect of the interconnected attributed. This dispersion effect leads to uneven spreading of the cells founded within the 3D spacing. However, gas foaming is a significant technology that fine-tunes scaffolds porous textures despite its limitations (Akalin & Selamoglu, 2019). This counter approach to the limitation entails the presence of the interconnections and pores of the dimension that responds effectively with the morphological needs of each specific cell form.

Compression Molding

Compression molding is a typical form of procedure whereby a preheated polymer is compressed in a mold cavity that is heated and opens (Ng et al., 2015). The dermatologist must close the top plug during the compression p...