Research

Manipal Develops New Way to Predict Birth Defects

Scientists are searching published databases for identifying new molecular players involved in the maintenance of stemness

Dr Kaushik Deb

A group of scientists from Manipal Institute of Regenerative Medicine and Stempeutics Research have for the first time shown that the presence of very low amounts of gram-negative bacterial lipopolysaccahrides (LPS) an endotoxin in the environment can cause defects in the development of tissues like the bones in a growing fetus. LPS is the main antigenic component of gram negative bacterial cell wall (causing vaginosis) and is regularly shed in the surrounding environment where the embryos grow. The findings, led by Dr Kaushik Deb, Group leader and Principal Scientist, Embryonic Stem Cell Programme, were recently published in the pioneering journal Regenerative Medicine.

Dr Deb said, "Ethical issues limit the study of molecular mechanisms underlying such pathogenesis in human embryos. We have therefore used embryoid bodies as a tool to understand the effect of the endotoxins on induction of lineages in a developing foetus. A molecular analysis of the embryoid bodies exposed to LPS indicated the complete silencing of expression for eight of the mesoderm tissue markers. These EBs were then tested for their ability to produce osteoblasts or bone tissues of mesoderm origin. As expected these EBs could not be differentiated to osteoblast. They had lost their ability to form functional osteoblasts cells". The expression of a LPS inducible and pluripotency-related gene high mobility group box 1 (HMGB1) was studied to assess its possible involvement in the aberrant differentiation of the LPS treated EBs.

Since inception, human embryonic stem cells have been perceived as the solution to many debilitating medical problems. Besides their potential application in thera pies, they also provide an unprecedented platform to study foetal development and the effect of environmental factors on them. Embryonic stem cells provide a reliable source for studying, in a Petri dish, the formation of all the 220 different tissues of the human body. Scientists can grow these cells as suspension cultures in low adhesion Petri dishes to produce early embryo like entities, known as embryoid bodies (EBs) which consist of a differentiated population of cells representing all the germ layers (the ectoderm, endoderm and mesoderm).

These EBs closely mimic a growing embryo in a mother's womb and consists of the placental precursor cells (trophectoderm) and also the cells of the embryo proper. It is now known that the skin and the nervous system arise from the ectoderm, the mesoderm forms tissues like the cardiomyocytes, bone and blood, and the endoderm forms the liver, lungs and intestine etc., of the developing embryo.

The early embryos growing in the mother's womb can cross-talk with the maternal environment, and respond to the factors around it. Common bacterial infections of the maternal genital tract, a clinical condition often termed as bacterial vaginosis, can lead to poor pregnancy outcomes. Sub clinical or silent infections of gram-negative bacteria like Chlamydia trachomatis etc can also cause birth defects with poorly developed tissues and organs of the fetus. However, an understanding on the molecular mechanisms of such pathogenesis remains obscure owing to ethical issues dogging the use of human embryos in research.

Dr Satish Totey, Chief Scientific Officer, Stempeutics Research, said, "Our scientists are searching published databases for identifying new molecular players involved in the maintenance of stemness. Here HMGB1 is explicitly expressed by the cells of the inner cell mass and is absent in the trophectoderm cells of the blastocyst, as reported in a previous study". Besides acting like a pro-inflammatory cytokine, HMGB1 is also a DNA-binding protein which can regulate the expression of several genes. Based on their findings, the researchers proposed that LPS induced HMGB1 was involved in the specific silencing of mesoderm induction.

"Because of its versatile roles both during development and in response to endotoxins, we hypothesised that HMGB1 may be a key player in mediating LPS induced developmental defects" said Dr Deb. He further stated; "Human embryonic stem cells are the gold standard for studying tissue formation and enable us to predict the effect of various pharmaceuticals/ drugs and natural toxins that the growing fetus may accidentally get exposed to, while inside the womb".

Dr Totey further added, "These findings have significant implications in birth defect research, and evaluation of developmental toxicity during drug screening. The entire work was supported and internally funded by Manipal University and the Stempeutics Research Pvt Ltd".

EH News Bureau