Tissue engineering, stem cells, cloning, and parthenogenesis: new paradigms for therapy

Abstract

: BACKGROUND: Patients suffering from diseased and injured organs may be treated with transplanted organs. However, there is a severe shortage of donor organs which is worsening yearly due to the aging population. Scientists in the field of tissue engineering apply the principles of cell transplantation, materials science, and bioengineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. Both therapeutic cloning (nucleus from a donor cell is transferred into an enucleated oocyte), and parthenogenesis (oocyte is activated and stimulated to divide), permit extraction of pluripotent embryonic stem cells, and offer a potentially limitless source of cells for tissue engineering applications. The stem cell field is also advancing rapidly, opening new options for therapy. The present article reviews recent progress in tissue engineering and describes applications of these new technologies that may offer novel therapies for patients with end-stage organ failure.

Figure 1

Strategy for therapeutic cloning and tissue engineering

Figure 2

Combining therapeutic cloning and tissue engineering to produce kidney tissue, an illustration of the tissue-engineered renal unit.

Figure 3

Renal unit seeded with cloned cells, three months after implantation, showing the accumulation of urinelike fluid.

Figure 4

Clear unidirectional continuity between the mature glomeruli, their tubules, and the polycarbonate membrane.

Figure 5

Elispot analyses of the frequencies of T-cells that secrete IFN-gamma after primary and secondary stimulation with allogeneic renal cells, cloned renal cells, or nuclear donor fibroblasts.