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Density-independent isolation of type II pneumocytes after partial pneumonectomy
B D Uhal1, G D Hess, D E Rannels
1Department of Physiology, College of Medicine, Pennsylvania State University, Hershey 17033.
Abstract:
Type II pneumocytes were isolated by immunoglobin G (IgG) panning from the lungs of normal rats and the right lung of rats (180-200 g) subjected to left pneumonectomy. Cells were studied at 7 (pnx-7) and 15 (pnx-15) days postoperative, times during and after, respectively, rapid compensatory growth of the right lung. After 24 h of primary culture, pnx-7 cells contained 32% more protein per DNA, and incorporated thymidine at a rate 224% greater than cells isolated from control rats. Both the protein-to-DNA ratio and thymidine incorporation returned to control values in pnx-15 cells. Uptake of exogenous spermidine also was increased by 50% in pnx-7 cells at 24 h of primary culture and returned to control values in pnx-15 cells. Increased spermidine uptake was due to an increase in the maximal velocity (Vmax) of transport from 30.3 (control) to 45.5 pmol.micrograms DNA-1.h-1 (pnx-7), with no change in the apparent Km of 1.32 microM. No change was observed in the relative rates of phospholipid or neutral lipid biosynthesis. The increases in thymidine incorporation and spermidine uptake were significantly greater than those previously observed [Am. J. Physiol. 254 (Cell Physiol. 23): C684-C690, 1988] in pnx-7 cells isolated by Percoll gradient sedimentation. These results suggest that pnx-7 lungs contain distinct subpopulations of type II pneumocytes, the recovery of which is dependent on the cell isolation protocol employed.
Insights
Following lung injury, specific type II pneumocytes show increased proliferation and spermidine uptake during compensatory growth. These changes, crucial for lung repair, depend on the cell isolation method used.
Area of Science:
- Cell Biology
- Pulmonary Medicine
- Regenerative Medicine
Background:
- Compensatory lung growth after pneumonectomy involves complex cellular processes.
- Type II pneumocytes are critical for lung repair and regeneration.
Purpose of the Study:
- To investigate the characteristics of type II pneumocytes during compensatory lung growth.
- To determine the impact of cell isolation techniques on these characteristics.
Main Methods:
- Isolation of type II pneumocytes from rat lungs using immunoglobulin G (IgG) panning post-pneumonectomy.
- Culturing cells at 7 and 15 days postoperative (pnx-7 and pnx-15).
- Assessing protein content, thymidine incorporation, and spermidine uptake.
Main Results:
- Pnx-7 type II pneumocytes exhibited 32% more protein per DNA and 224% greater thymidine incorporation than controls.
- Spermidine uptake increased by 50% in pnx-7 cells, attributed to increased Vmax of transport.
- These parameters returned to control levels by pnx-15.
- Observed increases were greater than with previous isolation methods, suggesting distinct cell subpopulations.
Conclusions:
- Compensatory lung growth involves distinct type II pneumocyte subpopulations with enhanced proliferative and metabolic activity.
- The recovery and characteristics of these cells are influenced by the isolation protocol.
- Immunoglobulin G panning may enrich for specific type II pneumocyte populations involved in lung repair.