Introduction
Biotechnology entails using “living organisms or their products to modify human health and human environment”. Although biotechnology dates to several millenniums ago when wine was fermented and bread was baked, the current advancements in the 20th and the 21st centuries are a hallmark in the field of medicine. The discovery of recombinant DNA technology opened a new chapter in biotechnology with new techniques in understanding human biology being unearthed. Among the technologies in biotechnology that gained popularity from the late 20th century is tissue engineering biotechnology. The technology is utilizing cell characteristics, like the ability to grow cells in vitro, to bring benefits to man specifically in repairing damaged and worn-out tissues and organs.
Tissue regeneration is also the same as tissue engineering whereby scaffolds are used to make new tissues and other biomaterials that are used to replace diseased or worn-out tissues or organs. A scaffold is a porous and biodegradable material derived from natural body proteins such as collagen and fibrin or they are synthetically produced from polymers such as polylactide or polyglycolide. A scaffold can also be synthetically derived by polymerizing polylactide with polyglycolide. Parveen and colleagues explain that a scaffold can vary in a structure such that there are spongy sheets and fabrics as well as gels. It is also possible to have scaffolds that are of higher complexity.
Essentially, scaffolds are made such that they mimic the extracellular matrix chemically and physically such that the in-vitro environment is similar to the in-vivo environment. The scaffolds usually contain donor cells that can differentiate such that they differentiate into the desired tissue once they are introduced into the body. Once a scaffold is introduced into the body for replacement of the worn-out or diseased tissue, the scaffold (which is biodegradable) undergoes resorption and healthy host tissues replace it. Tissue regeneration has come to solve an array of problems associated with organ and tissue transplants since the tissues are autologous. Tissue regeneration finds use in treating wounds from burns, hernias, in plastic surgery, and colorectal surgery among other applications. Tissue-engineered products have also been used to engineer skin, cartilage, and bone implantation.
The biotechnology field of tissue reconstruction as spearheaded by tissue engineering utilizes techniques such as nanotechnology to yield medical benefits. Nanotechnology in tissue regeneration, therefore, forms the next section of this work.
Nanotechnology in Tissue Regeneration
Nanotechnology is “the creation of objects or surfaces whose unique functions are a direct result of their nanoscale dimensions and/or organization”. A nanoscale dimension ranges from 1-100nm. Nanotechnology is a relatively new field even though it is growing very rapidly. When nanotechnology is applied in biotechnology, it is best referred to as nanobiotechnology. With nanotechnology, it is possible to treat some of the challenging human illnesses such as cancer, Alzheimer’s disease, Parkinson’s disease, and cardiovascular diseases among others.
The ability to manipulate molecules at the nanoscale has greatly advanced tissue reconstruction. Nanotechnology finds application in tissue regeneration procedures where it is possible to come up with an extra-cellular matrix that has a nanometer size thus enhancing the mimic of the in-vivo extra-cellular environment. A nanotechnology is therefore an indispensable tool in biomimetics as it helps in producing intelligent biomaterials and implants. The biomimetic and intelligent biomaterials can react accordingly with the extra-cellular environment with resultant stimulation of molecular-based regenerative events, thereby making healthy tissues. Through nanotechnology, it has been possible to come up with nanosize polymers that are important in reconstructive medicine. For instance, nanofibrous and porous scaffolds that are used in tissue reconstruction have been developed.
Nanofibres and nano guides are also available. Nanofibres are important in connecting the nano environment with the microenvironment and providing a large surface area such that tissue restoration does not only occur efficiently but also leads to compaction of organs and quick recovery. Parveen and colleagues also, describe that nanofabricated scaffolds can direct the fate of a cell in addition to monitoring angiogenesis and cell migration. With nanofabricated scaffolds, contact guidance and biocompatibility are enhanced greatly. At the same time, friction is reduced and the probability of revision surgery or tissue growth promotion is reduced.
The benefits of nanotechnology in tissue reconstruction are not limited to the production of resorbable biomaterials since it is possible to use nanotechnology to enhance the functioning and longevity of non-resorbable implants. This is done by coating the implant with bioactive nanoparticles such that the bonding between the implant and the neighboring tissue becomes more natural. Eventually, the biomaterials function better and attain a longer lifetime. The risk of immune rejection associated with implants can be avoided using nanotechnology, whereby a nanofabricated barrier covers the tissue implant such that the immune reactions of the host are not activated to reject the tissue. Biomaterials and composites usually experience mechanical failure associated with minor cracks and other shortcomings that are introduced when the materials are being loaded into the body. This problem can be averted by the use of nanomaterials that have better mechanical properties to withstand fatigue.
In neural prostheses, it is necessary to use biomaterials that have electrical processes. Conventional biomaterials however are limited in that they usually fail in their functioning with time. Nanotechnology can address this limitation by coming up with nanomaterials that have improved electrical properties such that they do not fail over the implantation period. Tissue regeneration is stimulated through the activation of the responsible genes. With nanotechnology, it is possible to come up with bioactive glasses as well as porous foams (macro-sized) that can activate the tissue regeneration stimulating genes. One can also visualize the application of nanotechnology in making biomaterials that have nanoscale features resembling the features of particular proteins. This can best be achieved by first comprehending tissues in terms of their contractile properties as well as propulsive properties.
Some Applications of Nanotechnology in Regenerative Medicine
Since nanobiotechnology is a relatively new field, there are not many successful applications in tissue reconstruction. The field is however very promising with studies in animal models being largely successful. The already successful tissue regeneration therapies are enough evidence of the reality of nanotechnology in tissue reconstruction. For instance, Harrington et al indicate that nanotechnology has been used to successfully repair damaged urinary bladder, making nanotechnology a great tool in urology research. Nanotechnology, therefore, enhances the efficacy of the stem cell made bladder. Currently, nanotechnology is being used in restoring hearing, specifically through cochlear implants. Bhowmik, Margret and Jayakar also mention the successful use of nanotubes in the treatment of bone fractures. The nanotubes provide a framework for the growth of new bone material.
As earlier stated, the promise of nanotechnology in regenerative medicine cannot be doubted going with the recent successes in animal studies. The next move from the clinical trials will be the clinical application of nanotechnology-based treatment of cardiovascular diseases, visual acuity, periodontal conditions as well as diabetes. Elloumi-Hannachi, Yamato and Okano have explored the clinical application of cell sheet engineering in regenerative medicine. The cell sheet engineering technique does not require a scaffold but rather uses poly(N-isopropyl acrylamide), a thermoresponsive polymer in reconstructing tissues in the above conditions.
In reconstructing the corneal surface, the cell sheet engineering technique utilizes a patient’s limbal stem cells or oral mucosal cells in improving visual acuity in patients suffering from Stevens-Johnson syndrome as well as alkali burns. Oesophageal ulcerations are treated through cell sheet technology uses epithelial cell sheets thus enhancing healing. Oesophageal carcinoma patients and patients undergoing endoscopy, therefore, stand to gain from nanotechnology. By using periodontal ligaments cells, cell sheet technology also corrects damaged periodontal tissue, at least in animal models, thus giving hope to periodontal damage patients. Elloumi-Hannachi, Yamato and Okano also, explain that nanotechnology-based cell sheet engineering can be applied in cardiomyopathies. The autologous cardiomyocyte cell sheets replace damaged cardiomyocytes regaining functioning effectively. This is a great leap towards treating often fatal cardiovascular diseases.
Conclusion
The field of biotechnology is limitless. Regenerative medicine has been revolutionized by the entry of nanotechnology and stem cell culture in the study of tissue regeneration. Through nanobiotechnology, it has been possible to explore tissue regeneration mechanisms at a nanoscale level thus enhancing the efficacy of tissue regeneration. From the makers of the nanofibrous scaffolds to the ability to enhance tissue differentiation in stem cells, nanotechnology has opened up a rich field that is indispensable in regenerative medicine. It is no wonder that it is possible to use the technology to make urinary bladders as well as produce tissue regenerative therapies for cardiovascular diseases, periodontal diseases, and diabetes treatment and improve visual acuity among other cures.
The ability to create a nanoscale environment that mimics the body’s extra-cellular matrix will continue to be hailed as a great achievement in regenerative medicine. This is because among the main challenges in tissue reconstruction is the establishment of an environment that is similar to the physiological environment. With nanotechnology, biomimicking is greatly enhanced thus solving this challenge. Indeed, one can only anticipate a future full of success in tissue reconstruction with the current upward trend in discoveries in nanotechnology.
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