Nanotechnology and stem cells are the two most exciting fields of modern research that promise to realise all the fantasies human kind has ever had. That of ageing, for instance. In the 1900s, average life expectancy was about 40 years. Today, it stands at 80 years. Will 2080 see a man living for 150 years? If yes, then do we have the resources to manage the health needs of this ageing population? Also, will a 150-year-old person have the same quality of life as a 40-year-old?
Such a scenario will set off a huge need for more tissue and organ regeneration to support extended life spans. Stem cells provide us with an unprecedented platform to study the functioning of our body cells and also equip us to devise treatment modalities.
However, to harness their potential, scientists need to work at the size scale of these tiny stem cells. Nanotechnology equips us with this capacity to look deep into the cells and manipulate them as per requirements. Effective amalgamation of these two technologies offers immense potential for the human race.
Nanotechnology is defined as the science and technology of nanoscale (one billionth of a meter), typically in the range 1-1000 nm. The genesis of nanotechnology dates back to the famous lecture by the Nobel laureate Prof Richard Feynman in 1960, when he said, “the principles of physics, as far as I can see, do not speak against the possibility of manoeuvring atom by atom.”
The essence of this statement lies in the fact that nanotechnology works at a depth where individual atoms and molecules are manipulated to obtain desired goals. It allows us to reach the most fundamental units which make materials around us and determine their behaviours (a typical atom is of the size of around 0.1 nm and proteins of life is 5 nm). The impact of nanotechnology has been felt in improved and sustainable sources of energy, miniaturised data storage disks, materials with super magnetic and optical properties, automated manufacturing assemblies, and smart fabrics. Nanotechnology in healthcare, also called nanomedicine or bio-nanotechnology is manifested in efficacious drug delivery systems, gene therapies, robotic based diagnostics and surgical aids, nano biomedical devices among others.
Indefinite proliferation of stem cells
Stem cells are distinguished from other cell types by their ability for indefinite proliferation and multi-lineage differentiation. State-of-the-art stem cell technologies and tissue engineering are enabling biologists to translate their findings into clinical therapeutics.
Efforts are being made to prompt stem cells to grow into all the 220 different body tissues under defined and reproducible conditions and assume characteristic 3-D morphologies.
Minerals, gems and metals are used in our own ancient medical systems like Ayurveda. The metals used for the preparation of these Ayurvedic concoctions were lead, tin, iron, silver, gold etc and their alloys. Analyses of some of these bhasmas (powders) by using modern analytical methods and equipment like electron microscopy have indicated that their average particle sizes range from 10 to 80 nano meters in diameter.
Studies have also indicated that these bhasmas have properties of rejuvenation and regeneration of tissues. Where silver bhasma was found to be good for nerve and skin rejuvenation, gold bhasma was found to enhance the numbers and quality of adult stem cells that reside in our body. To be able to appreciate the applications of nanotechnology in stem cell research, it is necessary to understand the research areas in this field.
Research in stem-cell nanotechnology can be divided into stem cell reprogramming, isolation and sorting, tissue engineering, molecular detection, visualisation of stem cells to monitor their in vivo fate, to engineering the genetic features of cells, and create a micro-environment suitable for their morphogenesis into clinically useful entities. The fate of stem cells is governed by the local microenvironment, the so-called stem cell niche, which comprise secreted growth factors, stem cell - neighbouring cell interactions, extracellular matrix (ECM) and mechanical properties.
Unspecialised to specialised
Nanotechnology can be utilised to create such an artificial microenvironment to determine mechanisms underlying the conversion of unspecialised stem cells into specialised cell types. Examples of such studies are to design (a) micro/nanopatterned surface to study stem cell response to topography, (b) nanoparticles to control the release of growth factors and biochemicals (c) nanofibres to mimic extracellular matrix (ECM).
Nanofabrication technologies have been used to guide stem cells to develop into three-dimensional tissue constructs. For example, nanofibres are able to provide an artificial extracellular scaffolding to promote regeneration of specific tissues. Nanopatterned or nanostructured scaffolds are also being designed to trigger stem cells to become specific cell types.
Traditionally, in several stem-cell based therapies, the cells are either injected into a patient or loaded on to biological scaffolds and placed at the site of injury. Any study on stem cells must first enable us to visualise and track changes associated with their morphogenesis and in-vivo delivery. Nanotechnology enables the tagging of stem cells using magnetic, genetic or fluorescent probes which can be monitored by magnetic resonance imaging (MRI) or fluorescence imaging.
However, there are questions related to the toxicity of these nanoparticles and safety of such applications in human beings. Therefore extensive screening is being carried out for selection of more inert and biologically compatible nanoparticles to tag the stem cells, for study in human beings in future.
Beside this, scientists are working on development of nanoparticle based gene delivery systems, for reprogramming adult cells to stem cells and in programming genetically altered human embryonic and adult stem cells, so as to improve their therapeutic efficiencies and applications. The antimicrobial property of certain nanoparticles and their synergestic effects with certain growth factors in improving stem cells proliferation is also turning up as an interesting area of research.
