Oral mucosa tissue engineering
Encyclopedia
Tissue engineering
of oral mucosa
combines cells, materials and engineering to produce a three-dimensional reconstruction of oral mucosa. It is meant to simulate the real anatomical structure and function of oral mucosa. Tissue engineered oral mucosa shows promise for clinical use, such as the replacement of soft tissue defects in the oral cavity. These defects can be divided into two major categories: the gingiva
l recessions (receding gums
) which are tooth-related defects, and the non tooth-related defects. Non tooth-related defects can be the result of trauma, chronic
infection or defects caused by tumor resection or ablation (in the case of oral cancer
). Common approaches for replacing damaged oral mucosa are the use of autologous grafts and cultured epithelial sheets.
.
Grafts used for oral reconstruction
are preferably taken from the oral cavity itself (such as gingival and palatal grafts). However, their limited availability and small size leads to the use of either skin transplants or intestinal mucosa to be able to cover bigger defects.
Other than tissue shortage, donor site morbidity is a common problem that may occur when using autologous grafts. When tissue is obtained from somewhere other than the oral cavity (such as the intestine or skin) there is a risk of the graft not being able to lose its original donor tissue characteristics. For example, skin grafts are often taken from the radial
forearm
or lateral
upperarm
when covering more extensive defects. A positive aspect of using skin grafts is the large availability of skin. However, skin grafts differ from oral mucosa in: consistency, color and keratinization pattern. The transplanted skin graft often continues to grow hair in the oral cavity.
layer and the bottom lamina propria
. The epithelial layer consists of four layers:
Depending on the region of the mouth the epithelium may be keratinized or non-keratinized. Non-keratinized squamous epithelium covers the soft palate
, lips, cheeks and the floor of the mouth. Keratinized squamous epithelium is present in the gingiva and hard palate
. Keratinization is the differentiation of keratinocyte
s in the granular layer into dead surface cells to form the stratum corneum. The cells terminally differentiate as they migrate to the surface (from the basal layer where the progenitor cell
s are located to the dead superficial surface).
The lamina propria is a fibrous connective tissue
layer that consists of a network of type I
and III
collagen
and elastin
fibers. The main cells of the lamina propria are the fibroblasts, which are responsible for the production of the extracellular matrix
. The basement membrane
forms the border between the epithelial layer and the lamina propria.
techniques make it possible to produce epithelial sheets for the replacement of damaged oral mucosa. Partial-thickness tissue engineering uses one type of cell layer, this can be in monolayers or multilayers. Monolayer epithelial sheets suffice for the study of the basic biology of oral mucosa, for example its responses to stimuli such as mechanical stress, growth factor
addition and radiation damage
. Oral mucosa, however, is a complex multilayer structure with proliferating and differentiating cells and monolayer epithelial sheets have been shown to be fragile, difficult to handle and likely to contract without a supporting extracellular matrix. Monolayer epithelial sheets can be used to manufacture multilayer cultures. These multilayer epithelial sheets show signs of differentiation such as the formation of a basement membrane and keratinization. Fibroblasts are the most common cells in extracellular matrix and are important for epithelial morphogenesis
. If fibroblasts are absent from the matrix, the epithelium stops proliferating but continues to differentiate. The structures obtained by partial-thickness oral mucosa engineering form the basis for full-thickness oral mucosa engineering.
situation because they take the anatomical structure of native oral mucosa into account. Problems, such as tissue shortage and donor site morbidity, do not occur when using full-thickness engineered oral mucosa.
The main goal when producing full-thickness engineered oral mucosa is to make it resemble normal oral mucosa as much as possible. This is achieved by using a combination of different cell types and scaffolds.
To obtain the best results, the type and origin of the fibroblasts and keratinocytes used in oral mucosa tissue engineering are important factors to hold into account. Fibroblasts are usually taken from the dermis
of the skin or oral mucosa. Kertinocytes can be isolated from different areas of the oral cavity (such as the palate or gingiva). It is important that the fibroblasts and keratinocytes are used in the earliest stage possible as the function of these cells decreases with time. The transplanted keratinocytes and fibroblasts should adapt to their new environment and adopt their function. There is a risk of losing the transplanted tissue if the cells do not adapt properly. This adaptation goes more smoothly when the donor tissue cells resemble the cells of the native tissue.
and stability should also be held into account. Available scaffolds for oral mucosa tissue engineering are:
Commercially available types are for example:
is the denatured form of collagen. Gelatin possesses several advantages for tissue-engineering application: they attract fibroblasts, are non-immunogenic , easy to manipulate and boost the formation of epithelium. There are three types of gelatin-based scaffolds:
Glucan
is a polysaccharide
with antibacterial, antiviral
and anticoagulant
properties.Hyaluronic acid is added to improve the biological and mechanical properties of the matrix.
is a polysaccharide that is chemically similar to cellulose
. Unlike collagen, chitosan biodegrades relatively slowly. However, chitosan is not very biocompatible with fibroblasts. To improve the stability of collagen and the biocompatibility of chitosan a compound is made by crosslinking the two; they compensate for each other's shortcomings.
Collagen-elastine membrane, collagen-glycosaminoglycane (C-GAG) matrix, cross-linked collagen matrix Integra™ and Terudermis® are other examples of compound collagen scaffolds.
contain fibrin which gives the keratinocytes stability. Moreover, they are simple to reproduce and handle.
When producing synthetic scaffolds there is full control over their properties. For example, they can be made to have good mechanical properties and the right biodegradability. When it comes to synthetic scaffolds thickness, porosity and pore size are important factors for controlling connective tissue formation.
Examples of synthetic scaffolds are:
Full-thickness engineered oral mucosa is mainly used in maxillofacial reconstructive surgery and periodontal peri-implant reconstruction. Good clinical and histological
results have been obtained. For example, there is vascular
ingrowth and the transplanted keratinocytes integrate well into the native epithelium. Full-thickness engineered oral mucosa has also shown good results for extra-oral applications such as urethral reconstruction, ocular
surface reconstruction and eyelid
reconstruction.
Tissue engineering
Tissue engineering is the use of a combination of cells, engineering and materials methods, and suitable biochemical and physio-chemical factors to improve or replace biological functions...
of oral mucosa
Oral mucosa
The oral mucosa is the mucous membrane epithelium of the mouth. It can be divided into three categories.*Masticatory mucosa, para-keratinized stratified squamous epithelium, found on the dorsum of the tongue, hard palate and attached gingiva....
combines cells, materials and engineering to produce a three-dimensional reconstruction of oral mucosa. It is meant to simulate the real anatomical structure and function of oral mucosa. Tissue engineered oral mucosa shows promise for clinical use, such as the replacement of soft tissue defects in the oral cavity. These defects can be divided into two major categories: the gingiva
Gingiva
The gingiva , or gums, consists of the mucosal tissue that lies over the mandible and maxilla inside the mouth.-General description:...
l recessions (receding gums
Receding gums
Receding gums refers to exposure in the roots of the teeth caused by a loss of gum tissue and/or retraction of the gingival margin from the crown of the teeth. Gum recession is a common problem in adults over the age of 40, but it may also occur starting from the teens...
) which are tooth-related defects, and the non tooth-related defects. Non tooth-related defects can be the result of trauma, chronic
Chronic
Chronic may refer to:* Chronic , a disease that is long-lasting and reoccurring.* Chronic toxicity, a substance with toxic effects after continuous or repeated exposure* The Chronic, a 1992 album by Dr. Dre...
infection or defects caused by tumor resection or ablation (in the case of oral cancer
Oral cancer
Oral cancer is a subtype of head and neck cancer, is any cancerous tissue growth located in the oral cavity. It may arise as a primary lesion originating in any of the oral tissues, by metastasis from a distant site of origin, or by extension from a neighboring anatomic structure, such as the...
). Common approaches for replacing damaged oral mucosa are the use of autologous grafts and cultured epithelial sheets.
Autologous grafts
Autologous grafts are used to transfer tissue from one site to another on the same body. The use of autologous grafts prevents transplantation rejection reactionsTransplant rejection
Transplant rejection occurs when transplanted tissue is rejected by the recipient's immune system, which destroys the transplanted tissue. Transplant rejection can be lessened by determining the molecular similitude between donor and recipient and by use of immunosuppressant drugs after...
.
Grafts used for oral reconstruction
Reconstructive surgery
Reconstructive surgery is, in its broadest sense, the use of surgery to restore the form and function of the body, although Maxillo-Facial Surgeons, Plastic Surgeons and Otolaryngologists do reconstructive surgery on faces after trauma and to reconstruct the head and neck after cancer.Other...
are preferably taken from the oral cavity itself (such as gingival and palatal grafts). However, their limited availability and small size leads to the use of either skin transplants or intestinal mucosa to be able to cover bigger defects.
Other than tissue shortage, donor site morbidity is a common problem that may occur when using autologous grafts. When tissue is obtained from somewhere other than the oral cavity (such as the intestine or skin) there is a risk of the graft not being able to lose its original donor tissue characteristics. For example, skin grafts are often taken from the radial
Radius (bone)
The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...
forearm
Forearm
-See also:*Forearm flexors*Forearm muscles...
or lateral
Lateral
Lateral may refer to:*Lateral , an anatomical direction*Lateral canal, a canal built beside another stream*Lateral consonant, an ℓ-like consonant in which air flows along the sides of the tongue...
upperarm
Arm
In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods...
when covering more extensive defects. A positive aspect of using skin grafts is the large availability of skin. However, skin grafts differ from oral mucosa in: consistency, color and keratinization pattern. The transplanted skin graft often continues to grow hair in the oral cavity.
Normal Oral Mucosa
To better understand the challenges for building full-thickness engineered oral mucosa it is important to first understand the structure of normal oral mucosa. Normal oral mucosa consists of two layers, the top stratified squamous epithelialStratified squamous epithelium
A stratified squamous epithelium consists of squamous epithelial cells arranged in layers upon a basement membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity...
layer and the bottom lamina propria
Lamina propria
The lamina propria is a constituent of the moist linings known as mucous membranes or mucosa, which line various tubes in the body ....
. The epithelial layer consists of four layers:
- Stratum basale (basal layer)
- Stratum spinosumStratum spinosumThe stratum spinosum is a layer of the epidermis found between the stratum granulosum and stratum basale. This layer is also referred to as the "spinous" or "prickle-cell" layer. This appearance is due to desmosomal connections of adjacent cells. Keratinization begins in the stratum spinosum....
(spinous layer) - Stratum granulosumStratum granulosumThe stratum granulosum is a thin layer of cells in the epidermis. Keratinocytes migrating from the underlying stratum spinosum become known as granular cells in this layer...
(granular layer) - Stratum corneumStratum corneumThe stratum corneum is the outermost layer of the epidermis, consisting of dead cells that lack nuclei and organelles. The purpose of the stratum corneum is to form a barrier to protect underlying tissue from infection, dehydration, chemicals and mechanical stress...
(keratinized/superficial layer)
Depending on the region of the mouth the epithelium may be keratinized or non-keratinized. Non-keratinized squamous epithelium covers the soft palate
Soft palate
The soft palate is the soft tissue constituting the back of the roof of the mouth. The soft palate is distinguished from the hard palate at the front of the mouth in that it does not contain bone....
, lips, cheeks and the floor of the mouth. Keratinized squamous epithelium is present in the gingiva and hard palate
Hard palate
The hard palate is a thin horizontal bony plate of the skull, located in the roof of the mouth. It spans the arch formed by the upper teeth.It is formed by the palatine process of the maxilla and horizontal plate of palatine bone....
. Keratinization is the differentiation of keratinocyte
Keratinocyte
Keratinocytes are the predominant cell type in the epidermis, the outermost layer of the human skin, constituting 95% of the cells found there. Those keratinocytes found in the basal layer of the skin are sometimes referred to as "basal cells" or "basal keratinocytes"...
s in the granular layer into dead surface cells to form the stratum corneum. The cells terminally differentiate as they migrate to the surface (from the basal layer where the progenitor cell
Progenitor cell
A progenitor cell is a biological cell that, like a stem cell, has a tendency to differentiate into a specific type of cell, but is already more specific than a stem cell and is pushed to differentiate into its "target" cell...
s are located to the dead superficial surface).
The lamina propria is a fibrous connective tissue
Connective tissue
"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...
layer that consists of a network of type I
Type-I collagen
Type-I collagen is the most abundant collagen of the human body.It is present in scar tissue, the end product when tissue heals by repair.It is found in tendons, the endomysium of myofibrils and the organic part of bone.- See also :* Collagen...
and III
Type-III collagen
Collagen alpha-1 chain is a protein that in humans is encoded by the COL3A1 gene, which is located on chromosome 2.- Function :Collagen alpha-1 chain is a fibrillar collagen that is found in extensible connective tissues such as skin, lung, and the vascular system, frequently in association with...
collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
and elastin
Elastin
Elastin is a protein in connective tissue that is elastic and allows many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Elastin is also an important load-bearing tissue in the bodies of...
fibers. The main cells of the lamina propria are the fibroblasts, which are responsible for the production of the extracellular matrix
Extracellular matrix
In biology, the extracellular matrix is the extracellular part of animal tissue that usually provides structural support to the animal cells in addition to performing various other important functions. The extracellular matrix is the defining feature of connective tissue in animals.Extracellular...
. The basement membrane
Basement membrane
The basement membrane is a thin sheet of fibers that underlies the epithelium, which lines the cavities and surfaces of organs including skin, or the endothelium, which lines the interior surface of blood vessels.- Composition :...
forms the border between the epithelial layer and the lamina propria.
Partial-thickness engineered oral mucosa
Cell cultureCell culture
Cell culture is the complex process by which cells are grown under controlled conditions. In practice, the term "cell culture" has come to refer to the culturing of cells derived from singlecellular eukaryotes, especially animal cells. However, there are also cultures of plants, fungi and microbes,...
techniques make it possible to produce epithelial sheets for the replacement of damaged oral mucosa. Partial-thickness tissue engineering uses one type of cell layer, this can be in monolayers or multilayers. Monolayer epithelial sheets suffice for the study of the basic biology of oral mucosa, for example its responses to stimuli such as mechanical stress, growth factor
Growth factor
A growth factor is a naturally occurring substance capable of stimulating cellular growth, proliferation and cellular differentiation. Usually it is a protein or a steroid hormone. Growth factors are important for regulating a variety of cellular processes....
addition and radiation damage
Radiation damage
Radiation damage is a term associated with ionizing radiation.-Causes:This radiation may take several forms:*Cosmic rays and subsequent energetic particles caused by their collision with the atmosphere and other materials....
. Oral mucosa, however, is a complex multilayer structure with proliferating and differentiating cells and monolayer epithelial sheets have been shown to be fragile, difficult to handle and likely to contract without a supporting extracellular matrix. Monolayer epithelial sheets can be used to manufacture multilayer cultures. These multilayer epithelial sheets show signs of differentiation such as the formation of a basement membrane and keratinization. Fibroblasts are the most common cells in extracellular matrix and are important for epithelial morphogenesis
Morphogenesis
Morphogenesis , is the biological process that causes an organism to develop its shape...
. If fibroblasts are absent from the matrix, the epithelium stops proliferating but continues to differentiate. The structures obtained by partial-thickness oral mucosa engineering form the basis for full-thickness oral mucosa engineering.
Full-thickness tissue engineered oral mucosa
With the advancement of tissue engineering an alternative approach was developed: the full-thickness engineered oral mucosa. Full-thickness engineered oral mucosa is a better simulation of the in vivoIn vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
situation because they take the anatomical structure of native oral mucosa into account. Problems, such as tissue shortage and donor site morbidity, do not occur when using full-thickness engineered oral mucosa.
The main goal when producing full-thickness engineered oral mucosa is to make it resemble normal oral mucosa as much as possible. This is achieved by using a combination of different cell types and scaffolds.
- Lamina propria: is mimicked by seeding oral fibroblasts, producing extracellular matrix, into a biocompatibleBiocompatibilityBiocompatibility is related to the behavior of biomaterials in various contexts. The term may refer to specific properties of a material without specifying where or how the material is used , or to more empirical clinical success of a whole device in...
(porous) scaffold and culturing them in a fibroblast differentiation medium. - Basement membrane: containing type IV collagen, lamininLamininLaminins are major proteins in the basal lamina , a protein network foundation for most cells and organs...
, fibronectinFibronectinFibronectin is a high-molecular weight glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. In addition to integrins, fibronectin also binds extracellular matrix components such as collagen, fibrin and heparan sulfate proteoglycans...
and integrins. Ideally, the basement membrane must contain a lamina lucidaLamina lucidaThe lamina lucida is a component of the basement membrane which is found between the epithelium and underlying connective tissue...
and a lamina densaLamina densaThe lamina densa is a component of the basement membrane zone between the epidermis and dermis of the skin, and is an electron-dense zone between the lamina lucida and dermis, synthesized by the basal cells of the epidermis, and composed of type IV collagen, anchoring fibrils made of type VII...
. - Stratified squamous epithelium: is simulated by oral keratinocytes cultured in a medium containing keratinocyte growth factors such as the epidermal growth factorEpidermal growth factorEpidermal growth factor or EGF is a growth factor that plays an important role in the regulation of cell growth, proliferation, and differentiation by binding to its receptor EGFR...
(EGF).
To obtain the best results, the type and origin of the fibroblasts and keratinocytes used in oral mucosa tissue engineering are important factors to hold into account. Fibroblasts are usually taken from the dermis
Dermis
The dermis is a layer of skin between the epidermis and subcutaneous tissues, and is composed of two layers, the papillary and reticular dermis...
of the skin or oral mucosa. Kertinocytes can be isolated from different areas of the oral cavity (such as the palate or gingiva). It is important that the fibroblasts and keratinocytes are used in the earliest stage possible as the function of these cells decreases with time. The transplanted keratinocytes and fibroblasts should adapt to their new environment and adopt their function. There is a risk of losing the transplanted tissue if the cells do not adapt properly. This adaptation goes more smoothly when the donor tissue cells resemble the cells of the native tissue.
Scaffolds
A scaffold or matrix serves as a temporary supporting structure (extracellular matrix), the initial architecture, on which the cells can grow three-dimensionally into the desired tissue. A scaffold must provide the environment needed for cellular growth and differentiation; it must provide the strength to withstand mechanical stress and guide their growth. Moreover, scaffolds should be biodegradable and degrade at the same rate as the tissue regenerates to be optimally replaced by the host tissue. There are numerous scaffolds to choose from and when choosing a scaffold biocompatibiltiy, porosityPorosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
and stability should also be held into account. Available scaffolds for oral mucosa tissue engineering are:
Naturally Derived Scaffolds
- Acellular Dermis. An acellular dermis is made by removing the cells (epidermis and dermal fibroblasts) from split-thickness skin. It has two sides: one side has a basal laminaBasal laminaThe basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often confused with the basement membrane, and sometimes used inconsistently in the literature, see below....
suitable for the epithelial cells, and the other is suitable for fibroblast infiltration because it has intact vessel channels. It is durable, able to keep its structure and does not trigger immune reactions (non-immunogenic). - Amniotic Membrane. The amniotic membrane, the inner part of the placentaPlacentaThe placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
, has a thick basement membrane of collagen type IV and laminin and avascular connective tissue.
Fibroblast-populated Skin Substitutes
Fibroblast-populated Skin Substitutes are scaffolds which contain fibroblasts that are able to proliferate and produce extracellular matrix and growth factors within 2 to 3 weeks. This creates a matrix similar to that of a dermis.Commercially available types are for example:
- Dermagraft™
- Apligraf™
- Orcel™
- Polyactive™
- Hyalograf 3D™
Gelatin-based Scaffolds
GelatinGelatin
Gelatin is a translucent, colorless, brittle , flavorless solid substance, derived from the collagen inside animals' skin and bones. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar...
is the denatured form of collagen. Gelatin possesses several advantages for tissue-engineering application: they attract fibroblasts, are non-immunogenic , easy to manipulate and boost the formation of epithelium. There are three types of gelatin-based scaffolds:
- Gelatin-glucan matrix
- Gelatin-hyaluronate matrix
- Gelatin-chitosan hyaluronic acid matrix.
Glucan
Glucan
A glucan molecule is a polysaccharide of D-glucose monomers linked by glycosidic bonds.Many beta-glucans are medically important.-Types:The following are glucans:-Alpha:...
is a polysaccharide
Polysaccharide
Polysaccharides are long carbohydrate molecules, of repeated monomer units joined together by glycosidic bonds. They range in structure from linear to highly branched. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure,...
with antibacterial, antiviral
Antiviral
Antiviral may refer to:*Antiviral drug*Antiviral protein*Antivirus software*Antiviral Therapy, an academic journal...
and anticoagulant
Anticoagulant
An anticoagulant is a substance that prevents coagulation of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis...
properties.Hyaluronic acid is added to improve the biological and mechanical properties of the matrix.
Pure Collagen Scaffolds
Collagen is the primary component of the extracellular matrix. Collagen scaffolds efficiently support fibroblast growth, which in turn allows keratinocytes to grow nicely into multilayers. Collagen (mainly collagen type I) is often used as a scaffold because it is biocompatible, non-immunogenic and available. However, collagen biodegrades relatively rapidly and is not good at withstanding mechanical forces. Improved characteristics can be created by cross-linking collagen-based matrices: this is an effective method to correct the instability and mechanical properties.Compound Collagen Scaffolds
Compound collagen-based scaffolds have been developed in an attempt to improve the function of these scaffolds for tissue engineering. An example of a compound collagen scaffold is the collagen-chitosan matrix. ChitosanChitosan
Chitosan is a linear polysaccharide composed of randomly distributed β--linked D-glucosamine and N-acetyl-D-glucosamine...
is a polysaccharide that is chemically similar to cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
. Unlike collagen, chitosan biodegrades relatively slowly. However, chitosan is not very biocompatible with fibroblasts. To improve the stability of collagen and the biocompatibility of chitosan a compound is made by crosslinking the two; they compensate for each other's shortcomings.
Collagen-elastine membrane, collagen-glycosaminoglycane (C-GAG) matrix, cross-linked collagen matrix Integra™ and Terudermis® are other examples of compound collagen scaffolds.
Fibrin-based Scaffolds
Fibrin-based scaffoldsFibrin scaffold
A fibrin scaffold is a network of protein that holds together and supports a variety of living tissues. It is produced naturally by the body after injury, but also can be engineered as a tissue substitute to speed healing...
contain fibrin which gives the keratinocytes stability. Moreover, they are simple to reproduce and handle.
Hybrid Scaffolds
A hybrid scaffold is a skin substitute based on a combination of synthetic and natural materials. Examples of hybrid scaffolds are HYAFF® and Laserskin®. These hybrid scaffolds have been shown to have good in-vitro and in-vivo biocompatibilities and their biodegradability is controllable.Synthetic Scaffolds
The use of natural materials in scaffolds has its disadvantages. Usually, they are expensive, not available in large quantities and they have the risk of disease transmission. This has led to the development of synthetic scaffolds.When producing synthetic scaffolds there is full control over their properties. For example, they can be made to have good mechanical properties and the right biodegradability. When it comes to synthetic scaffolds thickness, porosity and pore size are important factors for controlling connective tissue formation.
Examples of synthetic scaffolds are:
- Polyethylene terephtalate membranes (PET membranes)
- Polycarbonate-permeable membranes (PC membranes)
- Porous polylactic glycolic acid (PLGAPLGAPLGA or poly is a copolymer which is used in a host of Food and Drug Administration approved therapeutic devices, owing to its biodegradability and biocompatibility. PLGA is synthesized by means of random ring-opening co-polymerization of two different monomers, the cyclic dimers of glycolic...
)
Clinical applications: full-thickness engineered oral mucosa
Although it has not yet been commercialized for clinical use clinical studies have been done on intra- and extra-oral treatments with full-thickness engineered oral mucosa.Full-thickness engineered oral mucosa is mainly used in maxillofacial reconstructive surgery and periodontal peri-implant reconstruction. Good clinical and histological
Histology
Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is performed by examining cells and tissues commonly by sectioning and staining; followed by examination under a light microscope or electron microscope...
results have been obtained. For example, there is vascular
Vascular
Vascular in zoology and medicine means "related to blood vessels", which are part of the circulatory system. An organ or tissue that is vascularized is heavily endowed with blood vessels and thus richly supplied with blood....
ingrowth and the transplanted keratinocytes integrate well into the native epithelium. Full-thickness engineered oral mucosa has also shown good results for extra-oral applications such as urethral reconstruction, ocular
Ocular
Ocular may refer to:* Eye, an organ of vision that detects light* Eyepiece, the optical element closest to the eye in a telescope or microscope* Ocular scale, a type of scales in reptilesRomania:...
surface reconstruction and eyelid
Eyelid
An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...
reconstruction.