Abstract: The present invention provides Pre-term Placenta Extra-embryonic Tissue Cell (PPETC) populations, and methods of culturing, proliferating and expanding the same. The invention also provides methods of using such cells for therapeutic and diagnostic applications. The present invention provides a method for isolation of extra-embryonic cell population will which are to be obtained preferably from premature discarded placenta by a process of non-enzymatic digestion or mechanical disruption. The isolated cells are cultured in semi-solid glycosaminoglycan-based three-dimensional milieu supplemented with autologous umbilical cord-derived serum. The isolated cells which are expanded in semi-solid media will be formulated for intravenous injections to patients having end stage cystic fibrosis. A preferred method of formulating cells for intravenous injection and optimal cell number are described herein.