New study published by scientists from the Weizmann Institute of Science suggests that stem cells may be used for repairing damaged lung tissues. This discovery gives new hope for treating conditions like bronchitis, asthma, cystic fibrosis or emphysema, which affect more than 35 million Americans and are the second leading cause of death worldwide.

Embryo stem cells able to generate new lung tissue

The treatment method proposed by scientists at the Weizmann Institute of Science is based on the similarities between stem cells that reside in the lungs and those in the bone marrow. Bone marrow cells, when transplanted to a patient, manage to find their way through the blood and to navigate to the appropriate compartment where they differentiate, but only if that compartment has been cleared out previous to the transplant.

Acknowledging this and the resemblance between the two types of cells, Professor Yair Reisner of the Immunology Department of the Weizmann Institute decided to test the ability of lung stem cells to travel to a specific compartment after being transplanted to mice [1]. Before introducing the embryonic stem cells into mouse models of lung damage, the group of scientists cleared the lungs’ stem cell compartments, in order to make room for the transplanted cells.

The injected stem cells managed to reach the empty stem cells compartments and to settle in the lungs, where they differentiated into normal lung tissue, six weeks after transplantation. Results showed that new lung cells continued to be created from the transplanted stem cells 16 weeks after the intervention, leading to the healing of the damaged lungs and improving the breathing ability of mice.

The scientists intend to continue their research and explore this option further, so as to determine the correct dosage of drugs needed for preventing the rejection of the transplanted stem cells, and maybe create a bank of lung stem cells that would provide cells ready to be transplanted to patients with severe respiratory diseases.

Lung-specific ipscs, potential alternative to emrbyonic stem cells

This is not the first attempt to heal damaged lungs with stem cells transplant. In a previous study, scientists from the Boston University Medical Center managed to generate 100 new lines of lung-disease specific iPSC from patients with emphysema, cystic fibrosis and other similar conditions. Results suggest that the new stem cells could be used for transplantation in patients suffering from lung diseases, thanks to their ability to differentiate into endoderm cells that can give rise to lung tissue.

Darrell Kotton, the study’s lead author, highlighted the fact that iPSCs are easier to cultivate in lab conditions, do not require embryos and are genetically identical to the patient’s cells, so the risk of rejection in such transplants is a lot lower. The lung-specific iPSCs obtained by reprograming adult cells into a primitive stem cell state could therefore solve some of the hurdles impacting embryo stem cell research.

In this study, scientists used skin cells that were reprogrammed into primitive pluripotent stem cells, results showing that the iPSCs have the ability to multiply and differentiate into endoderm tissue, which is the natural precursor of lung cells [2].

References:

1. Chava Rosen, Elias Shezen, Anna Aronovich, Yael Zlotnikov Klionsky et al. – Preconditioning allows engraftment of mouse and human embryonic lung cells, enabling lung repair in mice, Nature Medicine, 2015, http://www.nature.com/nm/journal/vaop/ncurrent/full/nm.3889.html
2. Aba Somers, Jyh-Chang Jean, Cesar A. Sommer, Amel Omari et al. – Generation of transgene-free lung disease-specific human induced pluripotent stem cells using a single excisable lentiviral stem cell cassette, Stem Cells, 2010, 28 (10):1728, http://onlinelibrary.wiley.com/doi/10.1002/stem.495/full