Manipulating stem cells to make different kinds of tissues

Picture Credit: Saroj Yadav

The human body grows from the first cell that is formed when a sperm fertilizes an egg. This happens through a marvelous process called differentiation. The original cell, and a few that come into existence during the first few hours and days after the egg is fertilized, are jacks of all trades; they can evolve into any of the different types of specialized cells that make up each organ in the human body. With each step in the cell division process, however, differentiation progresses, making the new cells more and more specialized.

Picture Credit: Saroj Yadav

The ability of a cell to evolve into more than one kind of cell is referred to as pluripotency. This ability is a great asset and has immense potential in the treatment of various diseases and injuries. For example, it can be used to grow any kind of human tissue or organ to replace something that has been damaged or destroyed by injury or disease. However, pluripotency disappears in the fully differentiated adult cells that are highly specialized. Stem cells from embryos, on the other hand, have full pluripotency. Harvesting stem cells from embryos, however, raises serious ethical, religious and philosophical questions and therefore lack legal sanction all over the world.

Picture Credit: Bengt Nyman

As a result, scientists all over the world had been trying to find alternatives to using embryonic stem cells. A breakthrough was finally achieved by the Japanese scientist, Shinya Yamanaka, in 2006. Adult cells were, for the first time, induced to turn into pluripotential stem cells by introducing four specific genes into them. These cells are referred to as induced pluripotent stem cells (iPSC). A major advantage of iPSCs is that they can be used in therapeutics without the controversies faced in case of embryonic stem cells. iPSCs can be used as disease models as well as for creation of desired tissues and organs. This discovery won Yamanaka the Nobel prize in 2012. iPSCs have been generated through various methods that include use of retroviruses, plasmid DNA, mRNAs, miRNAs as well as proteins. The most efficient way to create iPSCs from differentiated cells is using retroviruses as the vector to introduce the requisite genes into these cells. However, because of the integrative nature of retroviruses there is a high risk of cancer. The problem associated with other approaches is their low efficiency.

Picture Credit: rei,Flicker

In spite of these limitations iPSCs are widely recognized for their huge potential as a source of tissues and organs and are being closely studied. Different protocols have been standardized by various labs to differentiate these cells into functional tissues. One of the methods is to use the actin and microtubule targeting molecules like cytochalasin and nocodazole respectively. Nocodazole is known to target microtubules and cause mitotic block in dividing cells. But it appears that the drug brings about different changes in pluripotent cells as compared to other dividing cells like cancer cells.
Ability of cells to proliferate is the basis of life. Proper transfer of genetic information from mother cell to daughter cells is vital. Failure to do so may lead to various types of diseases including cancer. Pluripotent stem cells which can multiply and differentiate into various types of cells require a very precise regulation of cell cycle. The regulation of cell cycle is well characterized in the cancer cells. However the embryonic stem cells do not share the same characteristics as the cancer cells.
Studies the world over have, so far, mostly focused on the regulation of the cell cycle in cancer cells. Any work that compares the response of different types of cells to microtubule targeting drugs, therefore, can be of immense value as this will give an insight into the cell division machinery that is functional in various types of cells. At the IITB-Monash Research Academy in Mumbai, research scholar Saroj Yadav is pursuing exactly this line of investigation.

Working under the guidance of Dr Dulal Panda of IITB and Dr Paul Verma of Monash University, Saroj has been working to compare the pluripotent stem cells and cancer cells with respect to their response to microtubule targeting molecules. The study aims to identify and understand the small cues that the pluripotent cells may take and respond to. A control over these cues is important if anyone wants to grow these cells in laboratory and derive different types of cells to study diseases, development and differentiation.
Says Saroj, "If we are able to identify a novel pathway involved in differentiation the same can be manipulated in different ways to get specific types of tissues. Identification of cell cycle regulatory mechanism would help in understanding the cell biology of pluripotent stem cells. This information will be useful in determining the culture conditions suitable for the proper proliferation of the cells." Since iPSCs are expected to be useful in therapeutics, in making disease models as well as in developmental studies, understanding their basic biology will be of immeasurable value.
Graduate research scholars of IITB-Monash Research Academy study for a dually-badged PhD from both IIT Bombay and Monash University, spending time at both institutions to enrich their research experience. IITB-Monash Research Academy is a collaboration between India and Australia that endeavours to strengthen scientific relationships between the two countries.

Research scholar: Saroj Yadav

Project title: Generation & characterization of cell cycle regulation of induced pluripotent stem cells (iPSCs)

Supervisors: Dr Dulal Panda (IITB) & Dr Paul Verma (Monash),

Contact details: sarojyadav@iitb.ac.in

Contact research@iitbmonash.org for more information on this, and other projects.