Recent developments with karyoplast regeneration and nuclear transplantation.

Karyoplasts and cytoplasts prepared by cytochalasin-induced enucleation techniques were used in the development of systems for large-scale nuclear transplantation and the regeneration of karyoplasts to reform whole viable cells. Ten to 20% of a preparation of mouse L929 karyoplasts remained viable. These bodies, purified from whole cells, cytoplasts, and nonviable karyoplats, contained less than 10% of the cytoplasm in whole cells. By the technique of mass nuclear transplantation, up to 40% of a culture of cytoplasts could be renucleated by fusion of karyoplasts to a monolayer of enucleated cells. More than 5 x 10(5) renucleated or true cytoplasmic-nuclear hybrid cells could be prepared from a single cytoplast monolayer culture.