This Is How Tissue Engineering - A Brief Overview On Stem Cell Technology Will Look Like In 10 Years Time.ABSTRACT
Tissue engineering is a multidisciplinary field that combines the principles of engineering, life sciences, material, cells, etc to create a functional organ to replace damaged tissue/organs.
The approach was to fulfil the needs of the growing number of patients on the waiting list for organ transplantation due to the failure of organs and the limited number of donated organs available for such procedures. This need continues to grow internationally. The development of therapies for patients with severe chronic diseases affecting major organs such as the heart, kidney, and liver would vastly increase the potential impact of tissue-engineering technologies. Similarly, diabetes mellitus is now known as an exploding epidemic with more than 200 million patients worldwide. Patients with type 1 diabetes could be treated by transplantation of surrogate β cells or neo-islets. Osteoporosis, Alzheimer’s and Parkinson’s Diseases, chronic kidney diseases, severe burns, spinal cord injuries knee, bone disorders, and birth defects, as targets of regenerative medicine.
Tissue engineering, as a subfield of regenerative medicine, will also focus on even more prevalent conditions in which the restoration of functional tissue would fulfil a currently unmet medical need. Some various components of tissue engineering are reparative cells (ex- stem cells) appropriate scaffold for transplantation and support, bio reactive molecules (cytokines and growth factors) that will support and help in regeneration/formation of the desired tissue.
A NEW TREND EMERGING IN TISSUE ENGINEERING
Reprogramming of cells
The possibility of directing reprogramming of cells according to our use opens a window to a vast range of new possibilities in tissue engineering and regenerative medicines. Differentiation of stem cells into different types of tissue or organ is still a major limiting factor in the area of tissue engineering mainly because of the complexity and multicellular structure of the tissues and organs. To overcome this limitation, it is highly demanded to have different cell types for tissue engineering which is considered to be as important as mimicking the physiological condition in vivo.
Due to their unique properties, stem cells and polymeric biomaterials are key design options for tissue engineering. stem cells are important substrates owing to their capacity to differentiate into a large number of new cells in response to the stimuli provided and are most likely to lead to functionally engineered tissue.
Figure: 1A major focus of tissue engineering, therefore, is to use functional polymers with appropriate character to control stem cell function.
Stem cells used for tissue engineering are of two types:
- pluripotent stem cells and
- multipotent stem cells.
Pluripotent stem cells include embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Self-renewing and pluripotency are some unique properties of pluripotent stem cells that make the embryonic complex developmental process possible for the integrated tissue-engineered systems. As the embryonic stem cells are isolated from the inner cell mass of the blastocyst during the embryological development period of an individual, their use in tissue engineering is controversial and more limited while more attention has been paid to adult stem cells as they are multipotent and have a larger capacity to differentiate into a limited number of cell types. Adult stem cells can be found in various adult tissue types including bone marrow, peripheral blood, adipose tissues, nervous tissues, muscles, dermis, etc.
Figure 2:- Classification of stem cell
In vivo, differentiation and self-renewal of stem cells are decided by the signals from their surrounding microenvironment. This microenvironment or “niche “which is composed of other cell types as well, as numerous chemicals, mechanical and topographical cues at micro scales, are believed to serve as signalling mechanisms to determine the cell-specific recruitment, migration, differentiation as well as the production of numerous proteins. In vivo, the cells are surrounded by a biological matrix made up of tissue-specific combinations of insoluble proteins, glycosaminoglycans, and inorganic hydroxyapatite crystals (in the bone) which are collectively known as the extracellular matrix (ECM). The varied composition of the ECM components not only contains a reservoir of cell-signalling motifs (ligands) and growth factors that guide cellular anchorage and behaviour but are also responsible for physical architecture and mechanical strength to the tissue.
In this dynamic environment, the bidirectional flow of information between the ECM and the cells mediates gene expression, ECM remodelling, and ultimately the tissue/organ function.
Cells encounter a very different, unfamiliar surfaces and environments when cultured in vitro or when they are implanted into the body. Hence, we approach to form chemical, mechanical, and biological cues mimicking the natural stem cell niche to direct the desired stem cell behaviour to facilitate the regeneration of desired tissues with special emphasis on using adult stem cells including MSCs and NSCs. By employing various novel approaches, tissue engineers are trying to incorporate topographical, mechanical, and chemical cues into biomaterials to help control stem cell fate decisions.
Figure 3: stem cells properties
The use of biomaterials as scaffolds may be an elementary part of tissue engineering since these materials function templates for tissue formation and are built relying on the tissue of interest. These scaffolds give structural and mechanical support for the cells likewise as gift cues causing tissue repair. The structure, morphology, degradation, and presentation of bioactive sites are all vital parameters in material design for these applications and should signal the differentiation of stem cells. Besides all the parameters associated with the biomaterials scaffold, there are other factors like chemical cues (e.g. soluble reagents in terms of each concentration and their gradient, medium pH), mechanical cues (e.g. fluid shear stress) and alternative kinds of cues (electric and magnetic field) that are believed to possess a vital result on vegetative cell behaviour. These factors are reviewed extensively elsewhere.
In tissue engineering leading the cells to differentiate at the proper time, within the right place, and into the proper constitution, needs associate setting providing an equivalent factor that governs cell processes in vivo. We’d like numerous biomaterials and external cues coming up with issues mimicking
The natural somatic cell microenvironment to direct the required somatic cell fate.
- Neuss, S., Apel, C., Buttler, P., Denecke, B., Dhanasingh, A., & Ding, X. et al. (2008). Assessment of stem cell/biomaterial combinations for stem cell-based tissue engineering. Biomaterials, 29(3), 302-313. https://doi.org/10.1016/j.biomaterials.2007.09.022
- Howard, D., Buttery, L., Shakesheff, K., & Roberts, S. (2008). Tissue engineering: strategies, stem cells and scaffolds. Journal Of Anatomy, 213(1), 66-72. https://doi.org/10.1111/j.1469-7580.2008.00878.x Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2475566/
- Lanza, R., Langer, R., & Vacanti, J. Principles of tissue engineering (5th ed.). Academic Press Publications. Retrieved from https://books.google.co.in/books?id=Fz_ZDwAAQBAJ&printsec=frontcover&source=gbs_atb#v=onepage&q&f=false
- Mashayekhan, S., Hajiabbas, M., & Fallah, A. (2020). Stem Cells in Tissue Engineering. Retrieved 27 May 2020, from https://www.intechopen.com/books/pluripotent-stem-cells/stem-cells-in-tissue-engineering
About the Author:
Mridula Vats, a graduate student of University School of Chemical Technology, GGSIP University, Delhi. She is pursuing her degree in biochemical engineering and is interested in biotechnology.