Harvesting stem cells from umbilical cord

After umbilical cord blood, the Chennai based LifeCell International is planning to save the umbilical cord tissue that is routinely discarded along with the placenta once a baby is delivered.

The cord tissue and cord blood are rich sources of stem cells.

LifeCell, which is into private banking, will start collecting umbilical cord tissue in the near future. It already collects and stores cord blood for private banking.

After a baby is delivered, the cord is first clamped before it is cut. Cord blood is collected and then the umbilical cord tissue is cut from the placenta to just above where it is clamped. About 20 cm of cord tissue is cut.

Unlike cord blood that is rich in haemopoetic (blood cell producing) stem cells, the umbilical cord tissue is rich in mesenchymal stem cells.

Mesenchymal stem cells are adult stem cells and are found in the bone marrow as well. These stem cells can form a variety of cells, including bone, cartilage, tendon, ligaments, fat and muscle.

Mesenchymal stem cells in the cord lining are found in the matrix (Wharton jelly). The concentration of mesenchymal stem cells in the cord varies from one cord to another.

Unlike separating the haemopoetic stem cells present in cord blood, separating mesenchymal stem cells is a lot more challenging.

Harvesting stem cells

The cord has to be cut into tiny pieces and the cord tissue has to be digested using enzymes for harvesting the mesenchymal stem cells.

“Digestion is a challenging task. It can affect the viability depending on the duration of digestion,” said Dr. Ajit kumar, Chief Scientific Officer, LifeCell. “But we have optimised the process.”

The approximate number of mononuclear stem cells per centimetre of cord is 1,00,000. “The mesenchymal stem cells are separated from the mononuclear ones,” said Dr. Kumar. “One in 300 mononuclear cells turns out to be a mesenchymal stem cell.” The separated stem cells are cultured to increase their numbers.

A 20 cm-long cord tissue would yield 5,000-6,000 mesenchymal stem cells. These stem cells are cultured and their numbers increase to 5-15 million through repeated multiplication.

“It takes about 3 weeks for the multiplication process,” said Dr. Kumar.

While the science of using haemopoetic stem cells found in cord blood to treat blood related diseases such as leukaemia is well established, the science of mesenchymal stem cells is at a nascent stage.

Though it may take many more years for various aspects of mesenchymal stem cell science to be validated, it makes sense not to throw away a valuable source of stem cells.

So far no public cord blood bank has ventured into storing cord tissue.

The cost

“It would cost Rs 40,000 to store cord tissue for 20 years, and Rs 75,000 to store cord blood for the same period, said Mr. Mayur Abhaya, President and Executive Director of LifeCell. “When both are stored it would cost Rs.1.15 lakh for a 20-year period.”

Published in The Hindu on March 19, 2009