Epithelia continually renews itself due to differentiating stem cells. Here, culture of bronchial stem cells destined for transplant and multiplication in the pulmonary alveoli. For the following reasons, adult stem cells may eventually prove to be better for cell therapy than embryonic stem cells: their greater availability in adult tissue; the absence of immune-response rejection; their decreased disposition for tumors. Removed from the patient, stem cells can be cultured and multiplied to attain a quantity that is sufficient to treat sickness or injuries.