Mesenchymal stem cells for lung diseases: focus on immunomodulatory action

In recent years, the morbidity and mortality caused by acute and chronic lung diseases have gradually increased, becoming a global public health burden. However, modern medicine has yet to determine the exact treatment for lung diseases associated with inflammation. Alleviating lung diseases and repairing injured lung tissue are urgent issues that need to be resolved. Mesenchymal stem cells (MSCs) have been used to treat various inflammatory diseases owing to their powerful anti-inflammatory, anti-apoptotic, and tissue-regenerative properties. MSCs show great promise and have been shown to play a role in relieving lung diseases experimentally. The immune regulatory role of MSCs is thought to be a key mechanism underlying their multiple potential therapeutic effects. Immune cells and secreted factors contribute to tissue repair following lung injury. However, the overactivation of immune cells can aggravate lung injury. Here, we review evidence that MSCs act on immune cells to relieve lung diseases. Based on the immunomodulatory properties of MSCs, the specific mechanisms by which MSCs in alleviate lung diseases are reviewed, with a focus on innate and adaptive immunity. In addition, we discuss current challenges in the treatment of lung diseases using MSCs.