Page 127 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

5.3 Progenitor stem cell therapy 125

Engineered stem cells can express a variety of antitumor agents and be a good help
for conventional chemotherapeutic agents [36]. But there is some limitation on it
particularly about the relationship between stem cells and normal cells which needs
more investigation on fundamental stem cell mechanisms which is demonstrating
the regulation of cancer cell proliferation because what makes cancer as a disease
is the unregulated self-renewal of these cells. Knowledge about fundamental of the
stem cells leads to improve therapeutics techniques and also it will improve stem
cell-based regenerative medicine and anticancer techniques [36].
Among stem cells, there is a kind of cell that is known as progenitor stem cells.
These cells today are shown to be useful in cancer immunotherapy [37]. Progenitor
cells often confused with adult stem cells; progenitor cells like stem cells can dif-
ferentiate to one or more kinds of cells but it cannot divide and reproduce unlimit-
edly. It can be said that they are between stem cells and fully differentiated cells.
Their potency depends on the type of their parent stem cells and their niche. These
cells like adult stem cells have the tendency to migrate toward the tissues where they
are needed. They found in adult organs and their main task is to repair the body.
Progenitor cells have little activity and they exhibit slow growth and mostly in the
case of tissue injury, or dead cells they can be activated. What makes the progenitor
cells to move and be activated is the growth factors and cytokines. Investigation of
cytokines and growth factors of progenitor cells is important to use these cells as an
antigen agent in cancer therapy [37,38].
Their limitation in differentiation and self-renewal make these cells to be more
attractive in cancer therapy [34,37]. Lymphocyte progenitor cells and hematopoi-
etic progenitor stem cells are important progenitor cells which are used in cancer
therapy.

5.3.1 Hematopoietic progenitor cells in cancer therapy
Tumor microenvironment recently being the center of researches and it includes a
component that it is shown they have an important role in the protection of cancer
stem cells. Microenvironment signals also can effect on renewal and differential of
normal cells. Hence, it is needed to understand the mechanism of all components
involved in cancer cell environment to monitor the metastatic process [39].
Hematopoietic stem cells are progenitor cells that are found in blood and bone
marrow. These cells act as a father cell and can be differentiated to the lymphocyte
and myeloid cells [40]. These cells are contributed to the monitoring of the meta-
static process. These cells have used in regenerative medicine and immunotherapy in
cancer therapy. Recent research on the production and mobilization of these progeni-
tor cells in patients with cancer and murine models have shown that hematopoietic
progenitor can produce a strengthen immunosuppressive milieu around the premeta-
static niche of distant regions [40]. This study was the first to track the development
of hematopoietic progenitor cells and its differentiation to myeloid cells that has the
suppressor effect on cancer cells. They present hematopoietic progenitor cells as a
direct powerful tool in cancer therapy.