Pluripotent Stem Cells Created From Monocytes

StemCellPatents.com, April 14, 2009

The U.S. Patent and Trade Office has awarded patent # 7,517,686 to scientists at the Blasticon Biotechnologische Forschung GmbH in Germany for their invention of a method by which dedifferentiated, programmable stem cells of monocytic origin are created. The invention also describes pharmaceutical applications and methods for differentiating the stem cells into target cells and tissue.

A type of white blood cell with distinct immunological properties, monocytes are conveniently obtained from peripheral blood which is easily drawn from a simple intravenous blood collection. Originally produced in the bone marrow from hematopoietic precursor cells known as monoblasts, monocytes play a central role in immune and inflammatory responses and are routinely measured for diagnostic purposes in a complete blood count.

The patent description includes methods for isolating monocytes from human blood, culturing the monocytes in a medium containing the cytokine and cellular growth factor M-CSF (macrophage colony stimulating factor) as well as IL-3 (interleukin-3), from which the dedifferentiated programmable stem cells are found to express the CD14, CD90 and CD123 antigens. As the authors explain in the "background" of their invention, "The use of embryonic stem cells has been the subject of extensive public discussion, especially in Germany, and is regarded as extremely problematical. Besides the ethical and legal problems connected with embryonic stem cells, the therapeutic use of such cells also comes up against difficulties. By nature, embryonic stem cells are obtained from donor organisms, which are heterologous vis-a-vis the potential recipients of differentiated cells or tissue (hereafter referred to as somatic target cells or target tissue) developed from these cells. It is therefore to be expected that such target cells will trigger an immediate immunological response in the potential recipients in the form of rejection." By contrast, the derivation of pluripotent stem cells from autologous monocytes that are collected from ordinary adult peripheral blood circumvents such difficulties.

As the authors further explain, "the foreseeable development of the age and disease profile of the population in the western world is decisive, leading to the expectation of a drastic turning point in the next 10 years in the health and care sector of the western European population, including the USA and Canada. In the Federal Republic of Germany alone, the demographic development suggests a 21% growth in population in the 45 to 64 year-old age group by 2015, and a 26% growth in the over-65 age group. This is bound to result in a change in patient structure and in the spectrum of diseases requiring treatment. Predictably, diseases of the cardio-circulatory system (high blood pressure, myocardial infarction), vascular diseases due to arteriosclerosis, and metabolic diseases such an diabetes mellitus, diseases of liver metabolism, kidney diseases as well as diseases of the skeletal system caused by age-related degeneration, and degenerative diseases of the cerebrum caused by neuronal and glial cell losses will increase and require innovative treatment concepts. These facts explain the immense national and international research and development efforts by the specialists involved, to obtain stem cells which can be programmed into differentiated cells typical of tissue (liver, bone, cartilage, muscle, skin etc.). The problem underlying the invention therefore resides in making available adult stem cells, the generation of which gives rise to no ethical and/or legal problems, which are rapidly available for the planned therapeutic use in the quantities required for this, and at justifiable production costs, and which, when used as 'cellular therapeutics' give rise to no side effects - or none worth mentioning - in terms of cellular rejection and induction of tumors, particularly malignant tumors, in the patient in question."

Within the claims of their invention the scientists propose methods for treating a number of diseases which include cirrhosis of the liver, pancreatic insufficiency, acute and chronic kidney failure, hormonal underfunctioning, cardiac infarction, pulmonary embolism, stroke and skin damage. Additionally, implantable prostheses for various anatomical structures such as cardiac valves and vessel prostheses as well as bone and joint prostheses are also described. Such claims are possible since the invention describes the dedifferentiation and redifferentiation of the monocytes into a variety of target cell and tissue types which include neuronal precursor cells, neurons and glial cells, endothelial cells, adipocytes (fat cells), hepatocytes (liver cells), keratinocytes (skin cells), and insulin-producing (pancreatic beta islet) cells. The authors further describe the coexpression of albumin and the monocyte-specific antigen CD14 in the hepatocytes, as well as the in vivo use of the cells in an animal model.

As the authors explain, "The generation of the stem cells according to the invention is completely harmless to the patient and - in the case of autologous use - comparable to own blood donation. The quantity of stem cells required for the usual therapy options can be made available cost-effectively within 10 to 14 days after the blood is taken. In addition the cell product provided for the therapy, in the case of autologous use, does not give rise to any immunological problem in terms of cell rejection, as cells and recipient are preferably genetically identical."

The claims of the invention also include an absence of the threat of cancerous malignancy, since, as the authors describe, "The stem cells according to the invention have also proved to be risk-free in animal experimentation and in culture with regard to giving rise to malignancy, a result which is only to be expected due to the cell of monocytic origin, from which the stem cells according to the invention derive."

Unlike the iPS (induced pluripotent stem) cells that are often in the news and which carry a number of risks not only because of their ability to form teratomas (tumors) but also because of the oncogenes (cancer causing genes) with which they are produced, these new stem cells of monocytic origin are created without oncogenes through a very different dedifferentiation process. The authors describe genetic transfection of the cells with the FAH (fumarylacetoacetate hydrolase) gene, and transfection with "multidrug resistant genes" such that "extended radical chemotherapy can be made possible in the case of malignant diseases by corresponding hematopoietic reconstitution, or radiation resistance can be produced."

Even though monocytes are ordinarily collected and separated from whole blood, they could also be alternatively obtained directly from organs, if necessary, such as in the case of contraindicating blood conditions such as anemia or leukemia, for example.

Although the patent was awarded today, the patent application was originally filed on November 21st of 2005.