Blood cells are regenerating constantly. Great deal of them appears in bone marrow. Bone marrow cells' transplantation is the only way to fight some blood diseases. And this blood-producing organ can be grown in a donor organism, which was demonstrated by Russian Academy of Sciences Institute of Developmental Biology. They transplanted mice fetuses' liver to adult mice and observed formation of a blood-producing bone marrow, covered with bony armor.
 

It is widely known that bones can appear outside the skeleton, when bone protein is introduced to animals. But they paid attention to blood-producing cells in these bones only in the turn of the millennium. Unfortunately, this technique of growing a blood-producing organ is inapplicable on mice, animals to which experimental hematology owes almost all its discoveries. Is it possible to produce one from cells, which still have no specialty, e.g. cells of some fetal tissues?
 

Moscow scientists have transplanted liver of 14-day-old mice under the renal capsule or subcutaneous connective tissue of adult animals. Most specialized liver cells die during first 24 hours after the transplantation, but its connective tissue cells stay alive, clone actively and start forming first little cartilages in two days. On the 5th day after the transplantation, a spongy bone, pierced with capillaries, starts to replace the cartilage; and on the 12-14th day the central part of this bone is populated with blood-producing cells. Stages of blood-producing organ formation have no strict time limitations, and one can observe both cartilage islets and bone tissue in the same sample.
 

If connective tissue cells of early mice fetuses' liver have almost no specialization and maintain their ability to become other tissues, newborn mice do not have such ability at all: transplantation of one- or two-day-old mice's liver do not cause formation of neither cartilage, nor bones. The scientists plan to specify the terms of possible transformation of liver cells to some other cells.
 

Bony capsule appears, when liver cells are transplanted rather under the renal capsule, than inside the connective tissue. The reasons why it is so still remain obscure, because blood-producing organ formation in mice was observed under conditions, the effect of which is very difficult to estimate. It is almost impossible to take into consideration the effect of both living and dying cells of a transplanted liver, as well as recipient's cells, tissues and immune system.
 

Thus, Russian scientists have discovered fantastic properties of fetal liver cells - they can transform to something totally different. Authors of the discovered phenomenon plan to break the system into components and to study cell cultures of fetal liver. Meanwhile, there are still too much questions to answer, thus not the right time for discussing this phenomenon's applications.