High-intensity sound waves raises hopes for regenerative medicine

Regenerative medicine deals with the replacing, engineering or regenerating human cells, tissues or organs to restore and establish normal function via stimulating body’s own repair mechanisms to functionally heal previously irreparable tissues or organs. Thus it offers solutions and hopes for people whose heath conditions are beyond repair.

Regenerative medicine refers to a group of biomedical approaches to clinical therapies that involves the use of stem cells. However, in order to use stem cells to generate new tissue or organs, a support network, which can function as a structural shell is needed. For this purpose, 3D scaffolds are used to mimic natural extracellular matrix, which acts as a structural template supporting cell adhesion, migration, differentiation, proliferation, and providing guidance for neo-tissue formation.

Researchers from the University of Washington have developed a new technique for the formation of a natural cellular scaffold. This method is tested to eliminate cancerous tumours. They used boiling histotripsy, a technique that uses millisecond-long bursts of high-intensity ultrasound waves to break apart tissues. Boiling histotripsy lesions are produced in a bovine liver with a clinical 1.2 MHz MR-HIFU system (Sonalleve, Philips, Finland), using 30 10-ms pulses and pulse repetition frequencies of 1-10 Hz. Peak acoustic powers corresponding to estimated in situ shock front amplitude of 65 MPa are used. The high power sound waves below 20 Hz are felt in the body but not heard by human ear as sound because the lower frequency limit of human hearing is 20 Hz.

After destruction of the tumours by sound, body gets rid of the degenerated tissue as cellular waste. However an intact fibrous framework or extracellular matrix is left behind. This framework offers a scaffold for the growing cells.

The method of histotripsy, is a fast decellularization of tissue with minimal damage to the matrix. The other decellularizing processes use of chemicals and enzymes and often takes several days and thus can damage matrix.

The scientists explain that, the intention of tissue engineering is to develop bio-mimetic structures so that the damaged tissue can be replaced with native one. So taking away damaged cells could be a good method as the extracellular matrix can act as cellular framework for the re-growth of cells. Moreover these matrixes could be nourished with stem cells from the host. Thus it is possible to redevelop a tissue by simply implanting the extracellular matrix into the body allowing the host body to self-seed the tissues, if it’s just a small patch of tissue which to be replaced. The healing would be better as there would not be any immune issues.

The researchers are now working on the decellularization of kidney and liver tissue from large animals. Future work for the team would involve increasing the size of the decellularized tissues and assessing their in-vivo regenerative efficacy.

Experts think that this is a significant milestone in regenerative medicine.

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Arunima Maiti

Arunima Maiti

Biomedical scientist with special interest in reproductive biology.

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