Regenerative medicine using human pluripotent stem cells to develop transplantable tissue outside the body carries the promise to deal with a range of intractable disorders, such as diabetes and Parkinson’s condition.
However , a research team from your Harvard Stem Cell Institute (HSCI), Harvard Medical College (HMS), and the Stanley Center for Psychiatric Research in the Broad Institute of MIT and Harvard has discovered that as stem cell lines grow in a laboratory dish, they often acquire mutations in the TP53 (p53) gene, an important tumor suppressor responsible for controlling cell growth plus division.
Their research suggests that genetic sequencing technologies should be used to screen for mutated cells within stem cell cultures, so that cultures with mutated tissue can be excluded from scientific experiments and clinical treatments. If such methods are not employed it could lead to an increased cancer risk in those receiving transplants.
The paper, published online in the journal Nature on April, 26, comes just the right time, the researchers said, as experimental remedies using human pluripotent stem cells are ramping upward across the country.
“Our results underscore the need for area of regenerative medicine to proceed with care, ” mentioned the study’s co-corresponding author Kevin Eggan, an HSCI Principal Faculty member and the director of stem cellular biology for the Stanley Center. Eggan’s lab in Harvard University’s Department of Stem Cell and Regenerative The field of biology uses human stem cells to study the mechanisms associated with brain disorders, including amyotrophic lateral sclerosis, intellectual impairment, and schizophrenia.
The research, the team mentioned, should not discourage the pursuit of experimental treatments but instead become heeded as a call to screen rigorously all cellular lines for mutations at various stages of growth as well as immediately before transplantation.
“Our results indicate that an additional series of quality control checks needs to be implemented during the production of stem cells and their particular downstream use in developing therapies, ” Eggan said. “Fortunately, these genetic checks can be readily performed with exact, sensitive, and increasingly inexpensive sequencing methods. ”
With human stem cells, researchers can reconstruct human tissue in the lab. This enables them to study the particular mechanisms by which certain genes can predispose an individual to some particular disease. Eggan has been working with Steve McCarroll, connect professor of genetics at Harvard Medical School plus director of genetics at the Stanley Center, to study exactly how genes shape the biology of neurons, which can be based on these stem cells.
McCarroll’s lab lately discovered a common, precancerous condition in which a blood stem cellular in the body acquires a pro-growth mutation and then outcompetes someone’s normal stem cells, becoming the dominant generator associated with his or her blood cells. People in whom this condition offers appeared are 12 times more likely to develop blood malignancy later in life. The study’s lead authors, Florian Merkle plus Sulagna Ghosh, collaborated with Eggan and McCarroll to try whether laboratory-grown stem cells might be vulnerable to an similar process.
“Cells in the lab, like tissues in the body, acquire mutations all the time, ” said McCarroll, co-corresponding author. “Mutations in most genes have little impact on the bigger tissue or cell line. But cells with a pro-growth mutation can outcompete other cells, become very several, and ‘take over’ a tissue. We found this process of clonal selection — the basis of cancer development in the body — is also routinely happening in laboratories. inch
To find acquired mutations, the researchers carried out genetic analyses on 140 stem cell lines — 26 of which were developed for therapeutic purposes making use of Good Manufacturing Practices, a quality control standard set simply by regulatory agencies in multiple countries. The remaining 114 had been listed on the NIH registry of human pluripotent stem tissue.
“While we expected to find some variations in stem cell lines, we were surprised to find that will about five percent of the stem cell lines all of us analyzed had acquired mutations in a tumor-suppressing gene known as p53, ” said Merkle.
Nicknamed the particular “guardian of the genome, ” p53 controls cell development and cell death. People who inherit p53 mutations create a rare disorder called Li-Fraumeni Syndrome, which confers the near 100 percent risk of developing cancer in a broad variety of tissue types.
The specific mutations that the scientists observed are “dominant negative” mutations, meaning, when existing on even one copy of P53, they are able to give up the function of the normal protein, whose components are manufactured from both gene copies. The exact same dominant-negative mutations are one of the most commonly observed mutations in human cancers.
“These precise mutations are very familiar to cancer researchers. They are among the worst P53 mutations to have, ” mentioned Sulagna Ghosh, a co-lead author of the study.
The researchers performed a sophisticated set of DNA studies to rule out the possibility that these mutations had been inherited instead of acquired as the cells grew in the lab. In following experiments, the Harvard scientists found that p53 mutant cells outperformed and outcompeted non-mutant cells in the laboratory dish. In other words, a culture with a million healthy tissues and one p53 mutant cell, said Eggan, could get a culture of only mutant cells.
“The spectrum of tissues at risk for transformation whenever harboring a p53 mutation include many of those that we want to target for repair with regenerative medicine using human being pluripotent stem cells, ” said Eggan. Those internal organs include the pancreas, brain, blood, bone, skin, liver plus lungs.
However , Eggan and McCarroll stressed that now that this phenomenon has been found, inexpensive gene-sequencing tests will allow researchers to identify and remove from the manufacturing line cell cultures with concerning mutations that might confirm dangerous after transplantation.
The researchers mention in their paper that screening approaches to identify these p53 mutations and others that confer cancer risk already can be found and are used in cancer diagnostics. In fact , in an ongoing medical trial that is transplanting cells derived from induced pluripotent come cells (iPSCs), gene sequencing is used to ensure the transplanted cellular products are free of dangerous mutations.