Chemistry: molecular biology and microbiology – Animal cell – per se ; composition thereof; process of... – Method of detaching cells – digesting tissue or establishing...
Reexamination Certificate
2001-10-09
2004-07-27
Guzo, David (Department: 1636)
Chemistry: molecular biology and microbiology
Animal cell, per se ; composition thereof; process of...
Method of detaching cells, digesting tissue or establishing...
C435S325000, C435S373000, C435S317100
Reexamination Certificate
active
06767740
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to methods and apparatus for recovering dental pulp from dentition of a patient or other donor, in order to use the pulp so secured, and the stem cells and other cells contained in the pulp, for beneficial medical purposes. More specifically, the present invention relates to a method of obtaining dental pulp from teeth at times and under conditions most suitable, such as during normal tooth loss of “deciduous” teeth. At such times teeth may be taken, and the pulp from within the teeth extracted or “harvested,” while preserving a sterile environment to avoid contamination of the pulp and, at the same time, avoiding trauma and infection of the donor. The pulp so secured may be utilized by isolating from it “stem cells,” which may exhibit an ability to differentiate into cells of the same or other types, or propagated and manipulated to exhibit such “plasticity,” for subsequent use in repair or regeneration of the same or other tissues of the body. The pulp may also be utilized by isolating from it other kinds of cells, such as dendritic cells which may exhibit an ability to detect hostile proteins foreign to a patient's body, for subsequent use in therapeutic treatments.
BACKGROUND ART OF THE INVENTION
In recent years, scientific interest has increased in cell biology in the areas of the derivation of cells, and the ability of certain cells to differentiate into cells of specific tissues. A broad interest in these areas dates back to the first report of animals produced by in vitro fertilization (“IVF”) in 1959, through the first report of the first fertilization of a human egg by IVF in 1968, and the report of the first IVF baby born in England in 1978. However, as a result of interest in developing innovative cell replacement strategies to rebuild tissues and restore critical functions of the diseased or damaged human body, some studies in these areas have more recently focused on the derivation and culturing of “stem cells,” and more particularly on human stem cells.
A stem cell is a cell that has the ability to divide (self replicate) for indefinite periods, often throughout the life of the organism. Under the right micro-environmental conditions, or given the right signals, stem cells can give rise (“differentiate”) to the many different cell types that make up the organism. That is, stem cells have the potential to develop into mature cells that have characteristic shapes and specialized functions, such as heart muscle, skin cells, hepatic tissues, or nerve cells.
It is widely recognized that a fertilized egg may generate all the cells and tissues that make up an embryo and that support its development in utero. The fertilized egg divides and differentiates until it produces a mature organism which, in mammals, requires the division of cells and their differentiation into more than 200 kinds of cells in the mature organism. These kinds of cells include nerve cells (neurons), blood cells (such as erythrocytes, monocytes, lymphocytes), and bone cells (osteocytes). “Pluripotent” stem cells can give rise to cells derived from all three embryonic germ layers (mesoderm, endoderm, and ectoderm) of an embryo, and much attention has therefore been focused recently on pluripotent stems cells from organisms at early stages of embryonic development. However, ethical concerns have been raised about the use of embryonic cells. As a result, adult (i.e., not embryonic) stem cells have taken on more importance as a source for stem cells for developing innovative therapeutic strategies.
An adult stem (“AS”) cell is an undifferentiated (unspecialized) cell that is found in a differentiated (specialized) tissue; it can renew itself and become specialized to yield all of the specialized cell types of the tissue from which it originated, and possibly other specialized cells. AS cells are capable of self-renewal for the lifetime of the organism. Cells capable of differentiating along only one lineage (i.e, “unipotent” cells, which allow a steady state of self-renewal), have been assumed for most tissues of adults until recently. Adult bone marrow cells, for example, have been known and used for decades in transplant therapies. However, even tissues containing only unipotent cells may be repaired if the tissue becomes damaged. When replacement of multiple cell types is required, pluripotent stems cells may become activated to repair the damage. Thus, for several decades stem cells harvested from skeletal bone marrow have been used in therapy in cases of cancer, aplastic anemia, lymphomas, and other life-threatening diseases. Sometimes marrow is transplanted directly from a donor to a patient requiring rescue therapy, and sometimes it is first preserved for a time in liquid nitrogen prior to transplantation.
It was not until recently that researchers have considered the possibility that stem cells in adult tissues could generate the specialized cell types of another type of tissue from that in which they normally reside. However, recent studies have demonstrated that blood stem cells (derived from bone marrow) may be able to generate both skeletal muscle and neurons. This facility of AS cells to generate specialized cell types of another type of tissue has been variously referred to as “plasticity,” “unorthodox differentiation,” or “transdifferentiation.” Presently, there is evidence that AS cells can generate mature, fully functional cells, or that the cells have restored lost function in vivo. Collectively, studies on plasticity suggest that stem cell populations in adult mammals are not fixed entities, and that after exposure to a new environment, they may be able to populate other tissues and possibly differentiate into other cell types.
Most studies on plasticity show plasticity in adult stem cells involving cells derived from bone marrow or brain tissue. Bone marrow appears to contain three stem cell populations, hemoatopoietic stem cells, bone marrow stromal cells, and (possibly) endothelial progenitor cells. Bone marrow stromal cells are a mixed cell population of cells that generate bone, cartilage, fat, fibrous connective tissue, and the reticular network that supports blood cell formation (mesenchymal stem cells of the bone marrow also give rise to these tissues, and may constitute the same population of cells as the bone marrow stromal cells). Studies of hematopoietic stem cells from bone marrow demonstrate an ability to regenerate an entire tissue system, i.e., all cell types found in blood. Thus, bone marrow shows promise as a source for AS cells exhibiting plasticity, and further development of materials and techniques may allow the utilization of all three stem cell populations found in bone marrow.
Efforts are now underway to take advantage of the newly found capability of adult stem cells, with the goal of devising new treatments for disease and disability. Medical science is now providing voluminous evidence of many potential uses for stem cells, such as organogenesis, gene therapy, anti-aging therapies, angiogenesis, organ and tissue repair (particularly in cases of nerve damage), and the treatment of brain tumors, liver disease, and other diseases. AS cells from marrow may now be treated with certain chemicals such as dimethyl sulfoxide (DMSO) and hetastard with PBS, cryopreserved in liquid nitrogen, and later removed, thawed and used for transplantation and other therapies. Today there is new evidence that AS cells may be found in more tissues and organs than previously thought, and that these cells are capable of developing into more kinds of cells than previously imagined. Efforts to devise new treatments for disease and disability utilizing AS cells hold great promise for the future if AS cells may be (i) secured from tissues of the body in a safe, painless, and convenient way, (ii) secured in acceptable quantity, (iii) isolated, (iv) propagated and aggregated (“expanded” via cellular division) to numbers useable for tissue regeneration, (v) and adapted to generate cell types of another type of
Javid Bahram
Sramek Roger Anton
Cook Thomas W.
Guzo David
Sullivan Daniel M.
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