Interstitial lung disease is a term used for a particular type of interstitium inflammation of the lungs. The interstitium is the tissue, surrounds and separates the tiny air sacs (alveolae) in the lungs. Interstitial lung disease involves an inflammation of this supportive tissue between the air sacs. The scarring (fibrosis) begins in Interstitium. This damage of lung tissue occurs due to known or unknown reason. ILD may called as Interstitial pulmonary fibrosis or pulmonary fibrosis.
ILD is not a single disease, but encompasses many different pathological processes. Hence treatment is different for each disease. It has been suggested that the medication may help slow the progression of lung damage without suppressing the immune system. Treatment may includes oxygen therapy, pulmonary rehabilitation and exercise therapy, vaccinations to avoids infections, lung transplantation etc.
Interstitial lung disease is mostly affect the adults, though it may also occurs in children. Certain interstitial diseases such as sarcoidosis, pulmonary Langerhans cell histiocytosis and autoimmune-associated lung diseases likely to affect the young adults, whereas idiopathic pulmonary fibrosis (IPF) most often occurs between the ages of 40 and 70.
The lung is a complex organ with limited regenerative capacity and lung injuries are leading causes of morbidity and mortality worldwide. It is believed that stem cells act through paracrine mechanism. Injured lung is thought to produce several chemokines, including hyaluronan, osteopontin, stromal-derived factor 1α, and secondary lymphoid chemokine, which interact with several receptors present on stem cells that stimulate proliferation of cells and migrate to sites of injury.
Regeneration of tissue by stem cells from endogenous, exogenous, and even genetically modified cells is a promising new therapy under evaluation for ILD, not responding to conventional therapy. Different studies are conducted to support that bone marrow progenitor cells contribute to repair and remodeling of lung in animal models of progressive pulmonary fibrosis. Recent studies have demonstrated paracrine effects of administered cells, including stimulation of angiogenesis and modulation of local inflammatory and immune responses in model mouse lung disease. Also some recent studies demonstrate that mesenchymal stem cells (MSCs) can modulate local inflammatory and immune responses in mouse lung disease models
Interstitial Lung Disease (ILD)
The pressures in the lung arteries (pulmonary arteries) are normally significantly lower than the pressures in the systemic circulation. But when pressure in the pulmonary circulation (pulmonary arteries) becomes abnormally elevated, it is referred to as pulmonary hypertension, pulmonary artery hypertension, or PAH.
Pulmonary hypertension generally results from constriction or stiffening of the pulmonary arteries that supply blood to the lungs, making it difficult for the heart to pump blood forward through the lungs. This stress on the heart leads to enlargement of the right heart and eventually fluid can build up in the liver and other tissues, such as in the legs.
Pulmonary hypertension is divided into two main categories; 1) primary pulmonary hypertension (not caused by any other disease or condition); Primary pulmonary hypertension has no identifiable underlying cause and is also referred to as idiopathic pulmonary hypertension. and 2) secondary pulmonary hypertension (caused by another underlying condition).
In patients with PPH, the average blood pressure in the pulmonary artery is greater than 25 mm Hg at rest and greater than 30 mm Hg during exercise. This abnormally high pressure (pulmonary hypertension) is due to changes in the small blood vessels in the lungs, which increase resistance to blood flowing through the vessels and puts a strain on the right ventricle to pump enough blood through the lungs.
In the United States, an estimated 500 to 1,000 new cases of primary pulmonary hypertension are diagnosed each year. The greatest number is reported in women between ages 20 and 40. However, men and women in all age ranges — as well as very young children — can develop PPH.
It is believed that Endothelial Progenitor Cells (EPCs) are involved in endothelial homeostasis, as well as physiological and pathological angiogenesis. It helps in replace the damaged blood vessels in the lungs of the pulmonary hypertension patients. Even patients no longer needs to be supplemented with oxygen or considered for a lung transplant. EPC-based therapies in patients with pulmonary hypertension show benefit of this approach, thus revealing EPCs as potential therapeutic targets. The clear advantage of EPCs would be their natural homing to the site of angiogenesis, which would target them to the site of muscle regeneration. It is hypothesized that neovascularization in the lung could increase the volume of the vascular bed in the pulmonary circulation and thus reduce the development of pulmonary hypertension (PH). These suggest that EPC transplantation can be a new therapeutic option for PPH.