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Uptake of isolated chloroplasts by mammalian cells
Abstract:
Mouse fibroblasts (L cells) in suspension culture incorporated isolated chloroplasts of spinach and African violets and isolated mitochondria of chicken liver. The organelles resided in the cell cytoplasm and were not contained in vacuoles or digestion vesicles. Green cells divided like normal cells. Green chloroplasts were followed for five cell generations or 5 days, at which time hybrid cells were greatly outnumbered by nongreen progeny cells. The ingested chloroplasts retained their structural integrity as determined by electron microscopy of organelles and hybrid cells and by analysis of photochemical activity and DNA in chloroplasts reisolated from cells after 1 or 2 days in culture.
Insights
Isolated chloroplasts were successfully integrated into mouse fibroblast cells, retaining function and structure through five cell divisions. However, these hybrid cells were eventually outnumbered by non-green cells, indicating limited long-term stability.
Area of Science:
- Cell Biology
- Organelle Transplantation
- Mitochondrial and Chloroplast Research
Background:
- Investigating the potential for inter-organismal organelle transfer and survival within a host cell.
- Understanding the functional integration and stability of isolated organelles in a foreign cellular environment.
Purpose of the Study:
- To determine if isolated chloroplasts and mitochondria can be successfully incorporated into mouse fibroblast (L cells) in suspension culture.
- To assess the structural integrity, viability, and functional capacity of these transplanted organelles within the host cell.
- To observe the behavior and stability of these hybrid cells over multiple cell generations.
Main Methods:
- Incubation of mouse fibroblasts with isolated spinach and African violet chloroplasts, and chicken liver mitochondria.
- Electron microscopy to examine the structural integrity of organelles and hybrid cells.
- Biochemical analysis of photochemical activity and DNA from reisolated chloroplasts.
- Long-term culture to track cell division and organelle persistence over five generations.
Main Results:
- Incorporated chloroplasts and mitochondria resided in the host cell cytoplasm, not within vacuoles.
- Transplanted chloroplasts maintained structural integrity and photochemical activity for up to 5 days (five cell generations).
- Hybrid cells divided normally, but non-green progeny cells eventually predominated, outnumbering the green cells.
Conclusions:
- Isolated chloroplasts can be successfully transplanted into mouse fibroblasts, maintaining structural and functional integrity in the short term.
- While the host cells divide, the transplanted chloroplasts do not appear to replicate or are diluted out, leading to their eventual loss.
- This study demonstrates the feasibility of organelle transplantation but highlights challenges in achieving long-term stable chimerism.