A team of scientists from Yale University states that it has accomplished a crucial initial step in the regeneration of completely functional lung tissue that can replace gas, which is the main role of the lungs. Their papers were published in the June issue of Science Express. Lung disease is responsible for nearly 400,000 deaths on a yearly basis in the United States. It is hard to regenerate lung tissue as it does not usually regenerate or repair beyond the microscopic level. The single existing method to replace impaired adult lung tissue is to carry out a lung transplantation, which is highly vulnerable to organ infection and rejection and realize merely 10 percent to 20 percent survival at 10 years.
The objective of the team of scientists from Yale was to see if it was likely to fruitfully implant tissue-engineered lungs, that have been cultured in vitro, that could serve the lung’s principal function of exchanging carbon dioxide and oxygen. The scientists took lungs of adult rats and initially removed their present cellular components, conserving the extra cellular matrix as well as hierarchical branching structures of the airways and vascular system in order to be used as scaffolds intended for the growth of novel lung cells.
Afterwards the scientists cultured a mixture of lung-specific cells on the extra cellular matrix, by making use of new bioreactor designed to imitate a few aspects of the fetal lung environment. Under conditions of the bioreactor similar to that of the fetal, the cells repopulated the decellularised matrix with fully functional lung cells. When the lungs were implanted into rats for short periods of time, around 45 to 120 minutes, the engineered lungs exchanged carbon dioxide and oxygen in the same way as natural lungs.
Laura Niklason, the lead author, who is also a professor and vice chairperson of the Departments of Anesthesiology and Biomedical Engineering of Yale University as well as a member of the Yale Medical Group, stated that they were able to engineer an implantable lung in their rat model that could effectively exchange carbon dioxide and oxygen, and could also oxygenate haemoglobin in the blood. She acknowledged that this is an initial step in the regeneration of complete lungs for bigger animals and, ultimately, for human beings.
The team of scientists discovered that the mechanical properties of the engineered lungs were comparable to those of native tissues and when they were implanted they were able to participate in gas exchange. She advanced that cultured and seeded epithelium exhibits noteworthy hierarchical organization in the lung matrix, whilst seeded endothelial cells effectively repopulate the lung vasculature.
The team of scientists from Yale University said that this is a significant initial step, however, a lot more research needs to be carried out to see if completely functional lungs can be regenerated in vitro, then implanted and subsequently sustained in their functioning. According to Niklason, in order for this technology to be applicable to patients, it is probable that years of research with adult stem cells will be required to repopulate lung matrix and create wholly functional lungs.
Source: Escience News and Yale
Wed, Jun 30, 2010
Nanotechnology, Stem cells