Stem Cells vs Cancer

Brigitte Hanly, Phd 
Embryonic Stem Cells vs Cancer Rebuttal

The most common scare regarding treatments with Embryonic Stem Cells ( ESC) comes from the alleged tumorigenicity of these cells. This document gathers published and unpublished data that shows how ESC not only do not cause cancer but also have the capacity to at least decrease malignancy and even prevent cancer.

About Tumorigenicity

The main article about tumorigenicity of ESC was published in 2008 on the journal Adv Cancer Res.  (Adv Cancer Res. 2008;100:133-58. doi: 10.1016/S0065-230X(08)00005-5.) titled “The tumorigenicity of human embryonic stem cells.” by Blum B1 and Benvenisty N.
In their abstract, they stated “Upon transplantation in vivo, undifferentiated hESCs rapidly generate the formation of large tumors called teratomas. These are benign masses of haphazardly differentiated tissues.” 
However, what this article like many others reporting about teratoma induced by ESC fails to mention is that all these teratomas are observed when ESC are introduced in recipients that have their immune system suppressed.

The following review published in StemCells Journal in February 2009 starts to explain that attempts to create teratomas with ESC fail when the immune system of the recipient is not depressed: “Deconstructing Stem Cell Tumorigenicity: A Roadmap to Safe Regenerative Medicine” by Paul S. Knoepfler, https://doi.org/10.1002/stem.37.
“In all such studies, particularly with a “negative” result where no teratoma were detected, it is unclear whether the apparent lack of tumorigenesis is related to the inherent properties of the transplanted stem cells or rather reflects the level of immunosuppression in the animal model being used (i.e., a false negative). Lack of teratoma in animal models with stem cell transplants may most often be reflective of a failure of engraftment due to immune cells in the host killing the stem cells.”
https://stemcellsjournals.onlinelibrary.wiley.com/doi/full/10.1002/stem.37

Further studies were clearer in showing the difference between immunosuppressed recipients and immunocompetent ones. 
In the results of “The Tumorigenicity of Mouse Embryonic Stem Cells and In Vitro Differentiated Neuronal Cells Is Controlled by the Recipients ’ Immune Response, Ralf Dressel et al. state:
“Embryonic stem (ES) cells have the potential to differentiate into all cell types and are considered as a valuable source of cells for transplantation therapies. A critical issue, however, is the risk of teratoma formation after transplantation. We have systematically compared the tumorigenicity of mouse ES cells and in vitro differentiated neuronal cells in various recipients. Subcutaneous injection of 1610 6 ES or differentiated cells into syngeneic or allogeneic immunodeficient mice resulted in teratomas in about 95 % of the recipients. Both cell types did not give rise to tumors in immunocompetent allogeneic mice or xenogeneic rats.”
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.275.6760

Researches have even been conducted to try stop the immune system to remove the implanted ESC. This article published on the journal Cell shows the “Effort to prevent the removal of teratoma” : (https://www.cell.com/cell-stem-cell/pdf/S1934-5909(13)00505-5.pdf) where they modify ESC before implantation in order to prevent the immune system to remove them.

All these efforts and studies about ESC becoming teratomas were in fact motivated by the belief that, to use ESC for therapy, these ESC needed to stay in the body. From our experience, generic ESC do not have a therapeutic effect by staying in the recipient system. Instead, they work by “signaling” repair, using their very unique microRNAs.

The study of the ESC exosome ( chemicals expressed by ESC) in fact lead to the discovery that not only ESC do not form teratomas in patients who do not take immunosuppressants, but they reduce cancer activity or prevent it.

ESC vs cancer cells. The anticancer effect of ESC exosome

At the same time that some researchers were publishing about tumorigenicity of ESC, others were showing that the environment created by ESC was actually changing cancer cells.

In J Cell Biochem. 2007 Jul 1;101(4):908-17, the article titled “The commonality of plasticity underlying multipotent tumor cells and embryonic stem cells by Postovit LM1 et al. states:
“By exposing aggressive cancer cells to embryonic microenvironments, the balance of regulatory mediators is restored, thereby reprogramming tumor cells to a more benign phenotype. These stem cell-derived mediators, as well as the genes they regulate, provide therapeutic targets designed to specifically differentiate and eradicate aggressive cancers.”
( https://www.ncbi.nlm.nih.gov/pubmed/17177292)

One year later  in Proc Natl Acad Sci U S A. 2008 Mar 18; 105(11): 4329–4334. “Human embryonic stem cell microenvironment suppresses the tumorigenic phenotype of aggressive cancer cells”  Lynne-Marie Postovit et al. said “exposure of the tumor cells to a hESC microenvironment (containing Lefty) leads to a dramatic down-regulation in their Nodal expression concomitant with a reduction in clonogenicity and tumorigenesis accompanied by an increase in apoptosis. Furthermore, this ability to suppress the tumorigenic phenotype is directly associated with the secretion of Lefty, exclusive to hESCs, because it is not detected in other stem cell types, normal cell types, or trophoblasts. The tumor-suppressive effects of the hESC microenvironment, by neutralizing the expression of Nodal in aggressive tumor cells, provide previously unexplored therapeutic modalities for cancer treatment.”
(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2393795/)

In the journal  Epigenomics. on December 2009, in the article titled “Epigenetically reprogramming metastatic tumor cells with an embryonic microenvironment”,  the authors went further into identifying the microRNAs that are down regulating cancer cells : “Using these experimental approaches, we identified miRNAs that are up- and down-regulated in melanoma cells exposed to a hESC microenvironment, such as miR-302a and miR-27b, respectively. We also demonstrate that Notch4 is one of the targets of miR-302a, which is upstream of Nodal. Additionally, one of the mechanisms that might explain the absence of the inhibitor of Nodal, Lefty, in cancer cells is silencing by DNA methylation, which provides new insights into the unregulated expression of Nodal in melanoma.”
https://www.ncbi.nlm.nih.gov/pubmed/20495621

More recently, in Cancer Biol Ther. on April 3, 2018, in the article titled . “Embryonic stem cell secreted factors decrease invasiveness of triple-negative breast cancer cells through regulome modulation” Tarasewicz E1 et al said in their abstract:
“Stem cell microenvironments decrease the invasiveness of cancer cells, and elucidating the mechanisms associated with disease regression could further the development of targeted therapies for aggressive cancer subtypes. To this end, we applied an emerging technology, TRanscriptional Activity CEll aRray (TRACER), to investigate the reprogramming of triple-negative breast cancer (TNBC) cells in conditions that promoted a less aggressive phenotype. The repressive environment was established through exposure to mouse embryonic stem cell conditioned media (mESC CM). Assessment of carcinogenic phenotypes indicated that mESC CM exposure decreased proliferation, invasion, migration, and stemness in TNBC cells.”
https://www.ncbi.nlm.nih.gov/pubmed/29053396

Different authors published similar results in the journal Stem Cell Research & Therapy in 2016 (https://doi.org/10.1186/s13287-016-0360-x)
“Embryonic stem cell preconditioned microenvironment suppresses tumorigenic properties in breast cancer” by Ningning He and al.

Their Results state:
“We used a real-time imaging system to investigate the effect of the mouse ES cell microenvironment on aggressive breast cancer cells in vitro and in vivo. Exposure of breast cancer cells in mouse ES cell conditioned medium resulted in inhibition of growth, migration, metastasis, and angiogenesis of cancer cells. For many tumors, aggressive properties were tightly related to Stat3 signaling activation. We specifically discovered that the ES cell microenvironment sufficiently suppressed Stat3 signaling pathway activation in aggressive tumor cells, leading to a reduction in tumorigenesis and invasiveness. In conclusion, we identified important functions of Stat3 and their implications for antitumor effects of ES cell conditioned medium. Some factors secreted by ES cells could efficiently suppress Stat3 pathway activation in breast cancer cells, and were then involved in cancer cell growth, survival, invasion, and migration. This study may act as a platform to understand tumor cell plasticity and may offer new therapeutic strategies to inhibit breast cancer progression.”
https://stemcellres.biomedcentral.com/articles/10.1186/s13287-016-0360-x

ESC as Cancer Vaccine

Other studies show that ESC also have the capacity to prevent cancer.

Here is a study about ESC preventing lung cancer development:
“Vaccination with Embryonic Stem Cells Protects against Lung Cancer: Is a Broad-Spectrum Prophylactic Vaccine against Cancer Possible?” by Kavitha Yaddanapudi et al. published on July 31, 2012 (https://doi.org/10.1371/journal.pone.0042289)
The Abstract states: “The antigenic similarity between tumors and embryos has been appreciated for many years and reflects the expression of embryonic gene products by cancer cells and/or cancer-initiating stem cells. Taking advantage of this similarity, we have tested a prophylactic lung cancer vaccine composed of allogeneic murine embryonic stem cells (ESC). Naïve C57BL/6 mice were vaccinated with ESC along with a source of granulocyte macrophage-colony stimulating factor (GM-CSF) in order to provide immunostimulatory adjuvant activity. Vaccinated mice were protected against subsequent challenge with implantable Lewis lung carcinoma (LLC). ESC-induced anti-tumor immunity was not due to a non-specific “allo-response” as vaccination with allogeneic murine embryonic fibroblasts did not protect against tumor outgrowth. Vaccine efficacy was associated with robust tumor-reactive primary and memory CD8+ T effector responses, Th1 cytokine response, higher intratumoral CD8+ T effector/CD4+CD25+Foxp3+ T regulatory cell ratio, and reduced myeloid derived suppressor cells in the spleen. Prevention of tumorigenesis was found to require a CD8-mediated cytotoxic T lymphocyte (CTL) response because in vivo depletion of CD8+ T lymphocytes completely abrogated the protective effect of vaccination. Importantly, this vaccination strategy also suppressed the development of lung cancer induced by the combination of carcinogen administration and chronic pulmonary inflammation. Further refinement of this novel vaccine strategy and identification of shared ESC/tumor antigens may lead to immunotherapeutic options for lung cancer patients and, perhaps more importantly, could represent a first step toward the development of prophylactic cancer vaccines.”

The following study is about ovarian cancer prevention by ESC: “Vaccination with embryonic stem cells generates effective antitumor immunity against ovarian cancer” by Zujuan Zhang et al. published on November 22, 2012     (https://doi.org/10.3892/ijmm.2012.1195)
The abstract states: “To date, only a few studies have suggested that human embryonic stem cells (hESCs) might effectively immunize against colon and lung cancer. The purpose of this study was to investigate the therapeutic potential of hESCs as a vaccine to induce widespread antitumor effects in different animal models and various types of cancer. C57BL/6 mice with ID8 ovarian cancer cell and Fischer 344 rats with NuTu-19 ovarian cancer cell models were used. Fifty-four mice were divided into six groups with nine mice in each group. Each mouse was immunized with pre-inactivated hESCs (H9) or mouse embryonic stem cells (mESCs; IVP-ES1) or ID8 or phosphate-buffered saline (PBS). Twenty-four rats were divided into four groups with six rats in each group, each rat immunized with pre-inactivated hESCs (H9) or NuTu-19 or PBS. After the vaccination, each mouse was challenged with live ID8 cells subcutaneously, and each rat was challenged with live NuTu-19 cells intraperitoneally. We discovered that vaccination of mice with the hESC line H9 and the mESC line IVP-ES1 generated consistent cellular and humoral immune responses against ID8 ovarian cancer. H9 and IVP-ES1 vaccinated mice obtained antitumor immune protection, and H9 vaccinated rats had the longest survival time and least distant metastases. No evidence of side-effects was observed. We also compared the immunogenicity against ovarian cancer between the hESC line, H9, and the mESC line, IVP-ES1, that derived from the inner cell mass in different species. We found that there were no significant differences between them. Furthermore, immunohistochemical staining revealed that several oncogenes and tumor suppressor genes, such as HER-2, C-myc, p53, and nm23, were expressed in H9, many of which were also shared by ovarian cancer. hESC vaccines can induce antitumor effects in two animal models and in ovarian cancer, indicating that the activity of the vaccine is universal, and, more importantly, it is safe.”

And a similar study showing how ESC prevent colon cancer in the journal Stem Cells. on December 2009 : “Vaccination with human pluripotent stem cells generates a broad spectrum of immunological and clinical responses against colon cancer.” by Li Y1and al., 

Here is the abstract: 
“The history of immunizing with embryonic materials to generate an antitumor immune response dates back to a century ago. The premise is that cancer cells share the expression of oncofetal antigens with embryonic materials and that the immune response against these antigens in the embryonic tissues is cross-protective against cancer. However, such a practice has never advanced beyond experimental animal settings, because of lack of uniformed source tissues and ethical challenges. With the availability of well-characterized human pluripotent stem cells, it is now possible to ask whether tumor protective immunity could indeed be elicited with stem cells. Herein, we investigated whether vaccination with defined human embryonic stem cells (hESCs) or induced pluripotent stem (iPS) cells was effective against a colon carcinoma. We discovered that vaccination of mice with hESC line H9 generated consistent cellular and humoral immune responses against CT26 colon carcinoma. Protection correlated strongly with the expansion of tumor-responsive and interferon-gamma-producing cells and the profound loss of CD11b(+)Gr-1(+) myeloid-derived suppressor cells in the spleen. No evidence of autoimmunity was observed. We also compared the immunogenicity against colon cancer between a hESC line CT2 and an iPS cell line TZ1 that were generated in the same stem cell facility. We found that the iPS cell line was inferior to the hESC line in conferring tumor protection, suggesting that there is heterogeneity of expression of oncofetal antigens by hESCs and iPS cells. We conclude that the hESC-based vaccine is a promising modality for immunotherapy of cancer.”
https://www.ncbi.nlm.nih.gov/pubmed/19816950

It is interesting to note in the above article that cancer prevention was stronger with hESCs than with iPsc ( induced pluripotent stem cells).

ESC vs Cancer : Clinical observations
(To be completed later)

Cases of CA19-9 reduction
Cases of CEA reduction

Cases of Lymphoma reduction

( before and after ESC blood tests)

Not available for public sharing yet

ESC mutations during culture and cancer?

More recently some have expressed concern about the possibility to receive ESC that would have mutated during culture.
Here is an article showing how ESC slowly show mutation during their passages:
https://onlinelibrary.wiley.com/doi/full/10.1002/bies.201670915
The most mutations are observed after 60 passages.
This well known issues is addressed by Stemaid scientists by never offering ESC that have been passed more than 40 times.

The article also explains that these mutations happen mainly with the semi automated way to culture them where enzymes are used during the passages. 

“Secondly, it is clear that the most labor‐intensive conditions, in which cells are physically cut into small pieces for passaging, keep the cells more genomically stable than techniques in which cells are dissociated enzymatically. Not only were there fewer duplications and deletions in mechanically passaged cells, but the duplications and deletions that arose were smaller (Fig. 2)”

Our laboratories use only the labor intensive, non enzymatic way to pass our ESC further avoiding possible damaging mutations.

Links to Embryonic Stem Cell Articles found at www.stemaid.com

 

DISCLAIMER:  The information on this site is for educational purposes only.  It is not intended as advice for self diagnosis or to replace medical care and are not a treatment or a cure for any illness or disease.