Stem cells can be developed into human lung organoids (organ-like tissue). Researchers have devised a novel method to support their growth and maturation using bio-artificial scaffolds.
The field of tissue engineering and artificial organs has brought substantial progress to healthcare research. Harvesting and developing primary human cells, generally known as stem cells, has led to the derivation of three-dimensional organ-like tissues (organoids). These organoids are developed in vitro, in an external environment and then transplanted inside a host body (mice).These organoids can be further used for research or treatment purposes.
Being similar to human fetal organs, these artificially developed tissues and can grow into functional organs or parts in the right environment. In a study, researchers developed a human lung organoid (HLO) that mimicked the fetal human lung. This three-dimensional tissue was then transplanted into the body of immune-compromised mice to explore if a functional set of lungs could develop from them. However, essential cell types and epithelial layer development did not occur, resulting in an incomplete and non-functional adult tissue. As a solution, the researchers hypothesized that use of a scaffold can create a niche (microenvironment) to support the stem cells and help the development process.The details of this experiment are described in a study published at elifesciences.org.
In order to observe the maturation and development of stem cells, 9 HLOs grown in vitro were transplanted under different conditions. The researchers transplanted 1-65 day mature HLOs, and harvested (retrieved from the mice) them at different times between 4 to 15 weeks. Using three different locations (kidney capsule, omentum and fat pad) as the transplant site, 5 HLOs were placed seeded on scaffolds and the rest were transplanted without using scaffolds. The tissues transplanted without scaffold were harvested and observed after 12 weeks. Irrespective of their maturity and location, the tissues did not show signs of lung epithelium development.The HLO transplanted within scaffolds were harvested twice, at 4 weeks and at 8 weeks. At 4 weeks, the HLO showed airway-like structures but no epithelium development. However, at 8 weeks researchers observed strong airway-like structures and multiple epithelial structures in the developed tissue.
Scaffolds are microporous rigid structures that provide support and favorable environment for tissue growth. The researchers also seeded HLOs into scaffolds in vitro and observed the tissue development. These HLOs displayed significantly less growth and no airway-like structure was observed. These results imply that the scaffold alone does not induce development but a combination of scaffold and in vivo environment brings about maturation for HLO epithelium.
The growth of artificial organs and tissue regeneration is now slowly becoming a reality with such research coming to light. Use of this technique for the growth of human lung organoids can lead to development of artificial lungs. Further studies can explore the use of scaffolds in development of stem cells into different human organs.
Written By: Anuja Galagali, Biomedical Engineer