Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Tissue
Reexamination Certificate
2001-02-23
2003-04-15
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Tissue
Reexamination Certificate
active
06547826
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to organogenesis, i.e. repair and/or neo-regeneration of tissues and organs in a mammalian body utilising autogenous stem cells of developed tissues. Particularly, the method of the invention is useful to regenerate or repair organs of endodermal origin such as bile duct, urinary bladder etc in vivo.
DEFINITIONS
Some of the terms used in the specification are defined herebelow for better understanding and clarity.
1. ‘Organogenesis’: is a term Generally used in embryology; it denotes the formation of organs from the fertilised ovum in developing embryo.
2. ‘Neo-Regeneration’ in biological terms means restoration of lost structures of a tissue organ or the tissue/organ itself. As used herein, the term includes restoration of not only the tissue or structures thereof, but also an attempt to restore functions performed by the tissue/organ.
3. Histogenesis: Formation of tissues of the body.
4. Plasia: Growth or a change (Latin—To mould).
5. Metaplasia: Change of cells from normal to abnormal state (Latin-Meta+plasia). Thus, transformation of a fully developed tissue into another fully developed tissue is known as metaplasia.
6. Desired Metaplasia: It is a kind of Metaplasia, but the transformed tissue containing stem cells is useful, needed, desired and compatible anatomically, physiologically and histologically, in the new region of exposure and is responsible for neo-regeneration of tissues and organs.
7. Stem cells: These cells are a kind of primitive cells present in an embryo or an adult body and have the capacity to differentiate into specialised tissues, having different functions. These cells can be defined in terms of their functional capabilities. Stem cell is not a property but a spectrum of capability.
8. Regeneration: The growth of destroyed or devitalised tissue or organ from the remnant tissue or organ. It is a reparative attempt of the body. This regeneration is different from neo-generation as it does not involve formation total tissue or organ and is not by colonisation or grafting tissue or cells which in turn undergo transformation and form new tissue.
9. Neo-organogenesis: Formation of tissue or organ by the transformation of stem cells on colonisation by differentiation and proliferation.
10. Neo-histogenesis: Formation of tissues by differentiation and proliferation of stem cells on colonisation in the tissues.
11. Contiguous embryonal segment: It is the region in an embryo from where the donor and recipient tissue/organ have developed and the same region corresponds in the adult/developed body.
12. Adult or developed body: Animal body where embryonal morphogenesis is complete and is capable of independent existence even though same tissues/organs may be still developing or adulthood has reached. Hence, the term “developed body” as used herein denotes a body in which embryonal morphogenesis is complete.
BACKGROUND OF THE INVENTION
In nature, plant life and lower animals display the capacity to re-grow their lost tissues and organs. For example, newts can grow their amputated eye lens, lobsters and crabs can grow their broken claws, lizards can grow their severed tails and frogs can grow their amputated legs.
Basic laws of nature remain hidden in the revealed world of nature. It is known that a fertilised egg undergoes various stages of morphogenesis and develops into an embryo and eventually into an adult. Morphologically, the early embryos of different species are strikingly similar. At this early stage of development of embryo it is difficult to differentiate between the embryos of different species, and one cannot say which embryo will become fish, bird, dog, pig, monkey or man. Thus, a single celled ovum forms an adult body having different organs and tissues with different structure and function. Multicellular bodies of higher life forms are formed by differentiation of and proliferation of embryonal primitive germ cells. In order to sustain complex life functions, the cell specialisation has to be maintained and thus, organ regeneration capacity is compromised in higher forms of life due to specialisation of stem cells and maintenance of specialisation.
The laws of nature are difficult to understand but have uniform applicability, in nature. Therefore, if lower life forms can re-grow lost parts, the applicant believes that such capacity may be present in higher life forms as well. As such, there are numerous attempts in the prior art to regenerate tissues and organs, each with variable rates of success. Some attempts comprise isolation of tissues from pigs and culturing the same to regenerate organs like liver or kidneys, in vitro. The major disadvantage with in vitro procedures is that they are very expensive, and therefore, not always affordable. Besides, there is always a problem of revascularization and acceptance of the organ regenerated in vitro by the human body. In other words, organ transplantation though a successful process, is plagued by rejection phenomenon which needs life long use of immuno-suppressants. This not only increases the cost but jeopardises the host immunity. Non-availability of suitable donor, preservation and transportation of organ are a few other problems associated with organ transplantation. Hence, it is always preferable to exploit the body's own potential to restore lost tissue/organs.
It is known that a fertilised ovum undergoes a series of divisions and forms a germ-layered disc. This disc consists of ectoderm, endoderm and mesoderm. These germ layers independently or in combination form various tissue and organs of an adult body. The endoderm of the embryonic germ disc forms a cavity lined by the cells of endodermal origin called ‘primary yolk sac’. A part of the cavity of the yolk sac is enclosed within the embryo to form the primitive gut, this gut is in free communication with the rest of the yolk sac. The part of the gut cranial (proximal) to this gut is the fore-gut; the part caudal is the hind-gut, while the intervening part is the mid-gut. The formation of these layers of the germ disc is attributed to the totipotent nature of the cells of the fertilized ovum. With the formation of the germ layers of germ disc, the cells lose their totipotent nature and become pluripotent, and as a consequence, these cells of the germ layers cannot form the whole body, but can only form certain tissues and body systems, derived from that specific germ layer. Thus, differentiation and specialisation of germ layer cells leads to specialised organ and tissues formation. Reverse activity i.e. formation of germ layer cells by the specialised tissue cells is not observed. Therefore, it is understood that the neo-regeneration of tissues requires pluripotent stem cells.
It is interesting to note that the stem cells developed from a particular layer of germ disc of developing embryo are present in some places in the developed tissues of adult body. These cells do maintain their pluripotent nature. In fact, “stem cells” by their great proliferative property maintain differentiated cell populations throughout the life of an animal (Ashman L. 1999, Stem Cells Encyclopedia of Molecular Biol. Vol.4. Ed. By TE Geighton, Publishers: John Wiley & Sons Inc. NY, Chichester, Weinheim, Brisbane, Singapore, Torento P. 2430-2433). The large division potential makes these cells efficient tissue regenerators through clonal growth (C.S. Potten MS Loeffler. Stem Cells; Attributes, cycles, spirals, pitfalls and uncertainties, lessons, far and from the crypt Dev. 110-1001-1020=1990. Review article). However, the exact loci where these stem cells are situated in an adult or developed body is not known.
The Applicant worked and used the principle that stem cells still exist in the adult body and retain their capacity to form various tissues given the right kind of environment and stimuli. The applicant has noted that the stem cells present in the developed body have lost their capacity to migrate because the development in the adult body is fixed on localised. Hence, the applicant has used the
Blanco Javier G.
Maulana Azad Medical College
Merchant & Gould P.C.
Willse David H.
LandOfFree
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