Rejuvenation Factor Discovered in Human Eggs


When the egg is fertilized by a sperm, it is transformed into a single-celled embryo or zygote that is metabolically active and driven to divide and develop. The egg, on the other hand, is a rather inert cell from a metabolic perspective. What is it in the egg that allows it to transform into something so remarkably different?

A new study by Swea-Ling Khaw and others in the laboratory of Ng Shyh-Chang at the Genome Institute of Singapore (GIS) has elucidated two main factors that help rejuvenate the egg and might also help reprogram adult cells into induced pluripotent stem cells (iPSCs).

Eggs express large amounts of a protein called Tcl1. Tcl1 suppresses the function of old, potentially malfunctioning mitochondria (the structure in cells that makes the energy for the cell). This suppression prevents damaged mitochondria from adversely affecting the egg’s transformation from into an embryo.

Remember also that if an adult cell is fused to an egg, it can cause the egg to divide and form an early embryo. Therefore, the egg cytoplasm is able to reprogram adult cells as well, and Tcl1 seems to play a role in this reprogramming capability as well.

In a screen for genes that are important to the reprogramming process, Shyh-Chang’s laboratory isolated two genes, Tcl1 and Tcl1b1. Further investigation of these two proteins showed that Tcl1 affects mitochondria by inhibiting a mitochondrial protein called polynucleotide phosphorylase (PNP). By locking PNP in the cytoplasm rather than the mitochondria, the growth and function of the mitochondria are inhibited. Tcl1b1 activates the Akt kinase, which stimulate cell growth, survival, and metabolism.

In a review article in the journal Stem Cells and Development, Anaïs Wanet and others explain that energy production in pluripotent stem cells is largely by means of glycolysis, which occurs in the cytoplasm. Mitochondria in pluripotent stem cells are immature subfunctional. When adult cells are reprogrammed into iPSCs, mitochondria function is shut down and energy production is largely derived from glycolysis. When the cells differentiate, the mitochondria are remodeled and become functional once again. Tcl1 is the protein that help shut down the mitochondria so that the pluripotent state can ensue and Tcf1b1 gears up the pluripotent stem cells to grow and divide at will.

Given this remarkable finding, can Tcf1 help make better iPSCs? Almost certainly, but how does one use this important factor to make better iPSCs?  That awaits further experimentation.  Additionally, this finding might also help aging and infertility issues as well. Hopefully this work by Shyh-Chang and her colleagues will lead to many more fruitful and exciting experiments.

Cells Made From Embryonic Stem Cells Derived from Cloned Embryos Are Rejected by the Immune System


Researchers from Stanford University have shown that genetic differences in mitochondria found in cells made from pluripotent stem cells that were originally derived from cloned embryos can prompt rejection by the immune system of the host animal from which they were made, at least in mice.

According to a study in mice by researchers at the Stanford University School of Medicine and colleagues in Germany, England and at MIT, cells and tissues in mice made from cloned embryos are rejected by the body because of a previously unknown immune response to the cell’s mitochondria. These findings reveal a likely hurdle if such therapies are ever used in humans.

Regenerative therapies that utilize stem cells have the potential to repair organs, replace dead or dying tissues, and treat severe diseases.  Many stem cell scientists think that pluripotent stem cells, which can differentiate into any kind of cell in the body, show the most promise for regenerative medical applications in the clinic.  One method for deriving pluripotent stem cells that have the same genetic composition as that of the patients is called somatic cell nuclear transfer (SCNT) or cloning.  This method takes the nucleus of an adult cell and injects it into an egg cell from which the nucleus has been removed.

SCNT can potentially make pluripotent stem cells that can repair a patient’s body. “One attraction of SCNT has always been that the genetic identity of the new pluripotent cell would be the same as the patient’s, since the transplanted nucleus carries the patient’s DNA,” said cardiothoracic surgeon Sonja Schrepfer, MD, PhD, who was the co-senior author of the study, which was published online Nov. 20 in Cell Stem Cell.

“The hope has been that this would eliminate the problem of the patient’s immune system attacking the pluripotent cells as foreign tissue, which is a problem with most organs and tissues when they are transplanted from one patient to another,” added Schrepfer, a visiting scholar at Stanford’s Cardiovascular Institute, and Heisenberg Professor of the German Research Foundation at the University Heart Center in Hamburg, and at the German Center for Cardiovascular Research.

Several years ago, Stanford University professor of pathology and developmental biology, Irving Weissman, MD, chaired a National Academies panel on SCNT cells.  At this time, he raised the possibility that the immune system of a patient who received the cells derived from stem cells made from cloned embryos might still generate an immune response against proteins from the cells’ mitochondria.  Mitochondria are the energy factories for cells, and they have their own genetic system (a DNA chromosome, protein-making structures called ribosomes, and enzymes for expressing and replicating DNA).  This reaction could occur because cells created through SCNT contain mitochondria from the egg donor and not from the patient, and therefore could still appear as foreign tissue to the recipient’s immune system.

There were other indications that Weisman was probably correct.  An experiment that was published in 2002 by William Rideout in the laboratory of Rudolf Jaenisch at the Whitehead Institute for Biological Research in the journal Cell derived embryonic stem cells from cloned mouse embryos and then differentiated those embryonic stem cells into bone marrow-based blood making stem cells. These blood making stem cells were then used to reconstitute the bone marrow of a mouse that had a mutation that prevented their bone marrow from forming normal types of disease-fighting white blood cells. However, even though the recipient mouse was genetically identical to the embryonic stem cells that had been used to derived the blood-making stem cells, the immune systems of the recipient mouse still rejected the implanted cells after a time.  Weissman, however, was not able to directly test this claim himself at that time.  Weissman directs the Stanford Institute for Stem Cell Biology and Regenerative Medicine, and now, in collaboration with Schrepfer and her colleagues, he was able to test this hypothesis.

“There was a thought that because the mitochondria were on the inside of the cell, they would not be exposed to the host’s immune system,” Schrepfer said. “We found out that this was not the case.”

Schrepfer, who heads the Transplant and Stem Cell Immunobiology Laboratory in Hamburg, used cells that were created by transferring the nuclei of adult mouse cells into enucleated eggs cells from genetically different mice. When transplanted back into the nucleus donor strain, the cells were rejected although there were only two single nucleotide substitutions in the mitochondrial DNA of these SCNT-derived cells compared to that of the nucleus donor. “We were surprised to find that just two small differences in the mitochondrial DNA was enough to cause an immune reaction,” she said.

“We didn’t do the experiment in humans, but we assume the same sort of reaction could occur,” Schrepfer added.

Until recently, researchers were able to perform SCNT in many species, but not in humans.  However, scientists at the Oregon Health and Science University announced the successful derivation of human embryonic  stem cells from cloned, human embryos.  This reignited interest in eventually using SCNT for human therapies. Although many stem cell researchers are focused on a different method of creating pluripotent stem cells, called induced pluripotent stem cells, some believe that there are some applications for which SCNT-derived pluripotent cells are better suited.

The immunological reactions reported in the new paper will be a consideration if clinicians ever use SCNT-derived stem cells in human therapy, but Weissman thinks that such reactions should not prevent their use.  “This research informs us of the margin of safety that would be required if, in the distant future, we need to use SCNT to create pluripotent cells to produce the tissue stem cells to treat someone,” he said. “In that case, clinicians would likely be able to handle the immunological reaction using the immunosuppression methods that are currently available.”  I find such a statement somewhat cavalier given that the nature of the immunological rejection might be robust enough to endanger the patient regardless of the anti-rejection drugs that are used.

In the future, scientists might also lessen the immune reaction by using eggs from someone who is genetically similar to the recipient, such as a mother or sister, Schrepfer added.  Except that now you have added the dangers of egg retrieval to this treatment regimen, which not only greatly jacks up the price of this type of treatment, but now endangers another person just to treat this one patient.  Add to that the fact that you are making a cloned human embryo (a very young person) for the sole purpose of dismembering it, and now you have added a degree of barbarism to this treatment as well.

So if we some SCNT-based treatments for patients we have an added danger for the patient (immunological rejection), danger for the egg donor, the homicide of the young embryo, and a prohibitively expensive procedure that no insurance company in their right mind would fund. I say we abandon this mode of treatment for the morally-bankrupt option that it is and pursue more ethical ways of treating patients.

Enzyme Helps Stem Cells Improve Recovery From Limb Injury


Ischemia refers to the absence of oxygen in a tissue or organ. Ischemia can cause cells to die and organs to fail and protecting cells, tissues and organs from ischemia-based damaged is an important research topic.

Perfusion refers to the restoration of the blood flow to an organ or tissue that had experienced a cessation of blood flow for a period of time. Even though the restoration of circulation is far preferable to ischemia, perfusion has its own share of side effects. For example, perfusion heightens cells death and inflammation and this can greatly exacerbate the physical condition of the patient after a heart attack, traumatic limb injury, or organ donation.

“Think about trying to hold onto a nuclear power plant after you unplug the electricity and cannot pump water to cool it down,” said Jack Yu, Chief of Medical College of Georgia’s Section of Plastic and Reconstructive Surgery. “All kinds of bad things start happening,”

Earlier studies in the laboratory of Babak Baban have shown that stem cells can improve new blood vessel growth and turn down the severe inflammation after perfusion (see Baban, et al., Am J Physiol Regul Integr Comp Physiol. 2012 Dec;303(11):R1136-46 and Mozaffari MS, Am J Cardiovasc Dis. 2013 Nov 1;3(4):180-96). Baban is an immunologist in the Medical College of Georgia and College of Dental Medicine at Georgia Regents University.

The new study from the Baban laboratory shows that an enzyme called indolamine 2,3,-dioxygenase or IDO can regulate inflammation during perfusion. IDO is widely known to generate immune tolerance and dampen the immune response in the developing embryo and fetus, but it turns out that stem cells also make this enzyme.

In their study, Including IDO with bone marrow-derived stem cells increased the healing efficiency of injected stem cells.

 Treatment Effect on Toe Spread Ratio Averages (48–72 hours after treatment). The outcome of stem cell (SC) therapy indicates that IDO may improve recovery. IDO-KO mice treated with SC demonstrated an accelerated recovery compared with IDO-KO treated with PBS (p-value <0.05). However, the WT mice treated with SC showed the greatest recovery of intrinsic paw function when expressed as a ratio comparing it to the non-injured paw (p-value = 0.027). Functional recovery from ischemia-reperfusion (IR) injury in the different treatment groups was measured, using a modified version of walking track analysis. For each subject, toe spread was measured in the IR limb (Ti) and control contralateral limb (Tc). The ratio of the toe spread in the injured limb (Ti) to the control limb (Tc) was then calculated by Ti/Tc. A ratio of 1 indicates 100% recovery or equal width and thus normal intrinsic function. When comparing the WT group treated with stem cells to those treated with PBS, a 45% increase in recovery was seen demonstrating the efficacy of stem cell therapy alone in the presence of an environment where IDO expression is present. doi:10.1371/journal.pone.0095720.g001
Treatment Effect on Toe Spread Ratio Averages (48–72 hours after treatment).
The outcome of stem cell (SC) therapy indicates that IDO may improve recovery. IDO-KO mice treated with SC demonstrated an accelerated recovery compared with IDO-KO treated with PBS (p-value <0.05). However, the WT mice treated with SC showed the greatest recovery of intrinsic paw function when expressed as a ratio comparing it to the non-injured paw (p-value = 0.027). Functional recovery from ischemia-reperfusion (IR) injury in the different treatment groups was measured, using a modified version of walking track analysis. For each subject, toe spread was measured in the IR limb (Ti) and control contralateral limb (Tc). The ratio of the toe spread in the injured limb (Ti) to the control limb (Tc) was then calculated by Ti/Tc. A ratio of 1 indicates 100% recovery or equal width and thus normal intrinsic function. When comparing the WT group treated with stem cells to those treated with PBS, a 45% increase in recovery was seen demonstrating the efficacy of stem cell therapy alone in the presence of an environment where IDO expression is present.
doi:10.1371/journal.pone.0095720.g001

Also indicators of inflammation, swelling, and cell death decreased in animals that received bone marrow-derived stem cell injections and had IDO.  Baban’s group also showed that the injected stem cells increased endogenous expression of IDO in the perfused tissues.

BMDScs can enhance IDO and regulatory T cells while reducing inflammatory cytokines in the hind limb IR injury. Immunohistochemical analysis of paraffin embedded tissues from murine model with IRI of hind limb showed that treating the animals with BMDSCs in an IDO sufficient microenvironment first: increased IDO and FOXP3 expression (panels A and B, red arrows), while decreased the inflammatory cytokines, IL-17 and IL-23 (panels C and D). Anti inflammatory cytokine, IL-10, was increased as demonstrated in panel E. All together, these analysis suggest a potential therapeutic role for BMDSCs, re-enforced by possible IDO dependent mechanisms. All pictures are 400X magnification
BMDScs can enhance IDO and regulatory T cells while reducing inflammatory cytokines in the hind limb IR injury.
Immunohistochemical analysis of paraffin embedded tissues from murine model with IRI of hind limb showed that treating the animals with BMDSCs in an IDO sufficient microenvironment first: increased IDO and FOXP3 expression (panels A and B, red arrows), while decreased the inflammatory cytokines, IL-17 and IL-23 (panels C and D). Anti inflammatory cytokine, IL-10, was increased as demonstrated in panel E. All together, these analysis suggest a potential therapeutic role for BMDSCs, re-enforced by possible IDO dependent mechanisms. All pictures are 400X magnification

Baban thinks that even though these experiments were performed in mice, because mice tend to be a rather good model system for limb perfusion/ischemia, these results might be applicable in the clinic.  “We don’t want to turn off the immune system, we want to turn it back to normal,” said Baban

According to Baban’s collaborator, Jack Yu, even a short period of inadequate blood supply and nutrients results in the rapid accumulation of destructive acidic metabolites, reactive oxygen species (also known as free radicals), and cellular damage.  The power plant of the cell, small structures called the mitochondria, tend to be one of the earliest casualties of ischemia/perfusion.  Since mitochondria require oxygen to make a chemical called ATP, which is the energy currency in cells, a lack of oxygen makes the mitochondria leaky, swollen and dysfunctional.

“The mitochondria are very sick,” said Yu. ” When blood flow is restored, it can put huge additional stress on sick powerhouses.  “They start to leak things that should not be outside the mitochondria.”

Without adequate energy production and a cellular power plant that leaks, the cells fill with toxic byproducts that cause the cells to commit a kind of cellular hari-kari.  Inflammation is a response to dying cells, since the role of inflammation is to remove dead or dying cells, but inflammation can give the coup de grace to cells that are already on the edge.  Therefore, inflammation can worsen the problem of cell death.

Even though these results were applied to limb ischemia perfusion, Baban and his colleagues think that their results are applicable to other types of ischemia perfusion events, such as heart attacks and deep burns.  Yu, for example, has noticed that in the case of burn patients, the transplantation of new tissue into areas that have undergone ischemia perfusion can die off even while the patient is still in the operating room.

“It cuts across many individual disease conditions,”  said Yu.  Transplant centers already are experimenting with pulsing donor organs to prevent reperfusion trauma.

The next experiments will include determining if more is better.  That is, if giving more stem cells will improve the condition of the injured animal.  In these experiments, which were published in the journal PLoS One, only one stem cell dose was given.  Also, IDO-enhancing drugs will be examined for their ability to prevent reperfusion damage.

Even though stem cells are not given to patients in hospitals after reperfusion, stem cell-based treatments are being tested for their ability to augment healing after reperfusion.  Presently, physicians reestablish blood flow and then give broad-spectrum antibiotics.  The results are inconsistent.  Hopefully, this work by Baban and others will pave the road for future work that leads to human clinical trials.

Stem Cells Heal Damaged Cells by Transferring Mitochondria


An Indian team from Delhi, India has identified a protein that increases the transfer of mitochondria from mesenchymal stem cells to lung cells, thus augmenting the healing of lung cells.

Stem cells like mesenchymal stem cells from bone marrow, fat, tendons, liver, skeletal muscle, and so on secrete a host of healing molecules, but they also form bridges to other cells and export their own mitochondria to heal damaged cells. Mitochondria are the structures inside cells that make energy. Damaged cells can have serious energy deficiencies and mitochondrial transfer ameliorates such problems (see Cárdenes N et al, Respiration. 2013;85(4):267-78).

This present work from the laboratory of Anurag Agrawal, who is housed in the Centre of Excellence in Asthma & Lung Disease, at the CSIR‐Institute of Genomics and Integrative Biology in Delhi, India has identified a protein called Miro1 that regulates the transfer of mitochondria to recipient cells.

Mitochondrial transfer has so many distinct benefits that stem cell scientists hope to engineer stem cells to transfer more of their mitochondria to damaged cells, and Miro1 might be a target for such stem cell engineering experiments.

Mitochondrial transfer between stem cells and other cells occurs by means of tunneling nanotubes, which are thread-like structures formed from the plasma membranes of cells that form bridges between different cell types. Under stressful conditions, the number of these nanotubes increases.

In the present study. stem cells engineered to express more Miro1 protein transferred mitochondria more efficiently than control stem cells. When used in mice with damaged lungs and airways, these Miro1-overexpressing cells were therapeutically more effective than control cells.

This study presents the first mechanistic insight into how Mesenchymal Stem Cells (MSC) act as mitochondrial donors during attenuation of lung inflammation and injury. Mitochondrial donation is an essential part of the MSC therapeutic effect in these models and is positively regulated by Miro1 / Rhot1 mitochondrial transport proteins.
This study presents the first mechanistic insight into how Mesenchymal Stem Cells (MSC) act as mitochondrial donors during attenuation of lung inflammation and injury. Mitochondrial donation is an essential part of the MSC therapeutic effect in these models and is positively regulated by Miro1 / Rhot1 mitochondrial transport proteins.

The hope is to use Miro1 manipulations to make better stem cell therapies for human diseases.

To summarize this work:

1. MSCs donate mitochondria to stressed epithelial cells (EC) that have malfunctioning mitochondrial.  Cytoplasmic nanotubular bridges form between the cells and Miro‐1 mediated mitochondrial transfer occurs unidirectionally from MSCs to ECs.

2. Other mesenchymal cells like smooth muscle cells and fibroblasts express Miro1 and can also donate mitochondria to ECs, but with low efficiency. ECs have very low levels of Miro1 and, as a rule, do not donate mitochondria.

3. Enhanced expression of Miro1 in mesenchymal cells increases their mitochondrial donor efficiency.  Conversely, cells lacking Miro1 do not show MSC mediated mitochondrial donation.

4. Miro1‐overexpressing MSCs have enhanced therapeutic effects in three different models of allergic lung inflammation and rat poison-induced lung injury.  Conversely, Miro1‐depleted MSCs lose much of their therapeutic effect.  Miro1 overexpression in MSCs may lead to more effective stem cell therapy.

Adding One Gene to Cells can Regrow Hair, Cartilage, Bone and Soft Tissues


The reactivation of a gene called Lin28a, which is active in embryonic stem cells, can regrow hair and repair cartilage, bone, skin, and other soft tissues in mice.

This study comes from scientists at the Stem Cell Program at Boston Children’s Hospital who found that the Lin28a promotes tissue repair by enhancing metabolism in mitochondria, which are the energy-producing engines in cells. These data suggest that upregulation of common “housekeeping” functions might provide new ways to develop regenerative treatments.

George Q. Daley, the director of Boston Children’s Hospital Stem Cell Transplantation Program, said, “Efforts to improve wound healing and tissue repair have mostly failed, but altering metabolism provides a new strategy which we hope will prove successful.”

One of the first authors of this paper, Shyh-Chang Ng, added, “Most people would naturally think that growth factors are the major players in wound healing, but we found that the core metabolism of cells is rate-limiting in terms of tissue repair. The enhanced metabolic rate we saw when we reactivated Lin28a is typical of embryos during their rapid growth phase.”

Lin28a was first discovered in worms, but the Lin28a gene is found in all animals. It is abundantly expressed in embryonic stem cells and during early embryonic development. Stem cell scientists have even used Lin28a to help reprogram adult cells into induced pluripotent stem cells. Lin28a encodes an RNA-binding protein that regulates the translation of messenger RNAs into protein.

To express more of this protein in mice, Daley and his colleagues attached the Lin28a gene to a piece of DNA that would drive expression when the mice were fed the drug doxycycline. Ng and others noticed that one of the targets of Lin28a was a small RNA molecule called Let-7, which is known to promote aging and cell maturation. Let-7 is a member of a class of non-coding RNA molecules called micro-RNAs that bind to messenger RNAs and prevent their translation.  Let-7 is made as a larger precursor molecule that is processed to a smaller molecule that is functional.  LIN28 binds specifically to the primary and precursor forms of Let-7, and inhibits Let-7 processing.

Lin28a function

Ng said, “We were confident that Let-7 would be the mechanism, but there was something else involved.”

Let-28a is known to activate the translation of several different genes that play a role in basic energy metabolism (e.g., Pfkp, Pdha1, Idh3b, Sdha, Ndufb3, and Ndufb8), Activation of these genes enhances oxidative metabolism and promotes an embryonic bioenergetic state.

In their Lin28a transgenic mice, Daley, Ng and others noticed that Lin28a definitively enhanced the production of metabolic enzymes in mitochondria, and that these “revved up” the mitochondria so that they generated the energy needed to stimulate and grow new tissues.

PIIS0092867413012786.fx1.lrg

“We already know that accumulated defects in mitochondria can lead to aging in many cells and tissues,” said Ng. We are showing the converse: enhancement of mitochondrial metabolism can boost tissue repair and regeneration, recapturing the remarkable repair capacity of juvenile animals. ”

Further experiments showed that bypassing Lin28a and directly activating mitochondrial metabolism with small molecules had the same effect on wound healing. This suggests that pharmaceuticals might induce regeneration and enhance tissue repair.

“Since Lin28 itself is difficult to introduce into cells, the fact that we were able to activate mitochondrial metabolism pharmacologically gives us hope,” said Ng.

Lin28a did not cause universal regeneration of all tissues. Heart tissue, for example, was poorly aided by Lin28a. Also, Lin28a induced the regeneration of severed finger tips in newborn mice, but not in adult mice.

Nevertheless, Lin28a could be a key factor in constituting a kind of healing cocktail, in combination with other embryonic factors yet to be found.

Inhibition of a Heart-Specific Enzyme After a Heart Attack Decreases Heart Damage and Prevents Remodeling


Cardiac Troponin I-interacting Kinase or TNNI3K is an enzyme that was initially identified in fetal and adult heart tissue, but was undetectable in other tissues. The function of this enzyme remains unknown, but Chinese scientists showed that overexpression of TNNI3K in cultured heart muscle cells causes them to blow up and get large (hypertrophy). Earlier this year, a research team from Peking Union Medical College showed that overexpression of TNNI3K in mice caused enlargement of the heart (Tang H., et al., J Mol Cell Cardiol 54 (2013): 101-111). These results suggested that TNNI3K is a potential therapeutic target for heart attack patients.

To that end, Ronald Vagnozzi and his colleagues in the laboratory of Thomas Force at Temple University School of Medicine and their collaborators designed small molecules that can inhibit TNNI3K activity, and these small molecules decrease cardiac remodeling after a heart attack in rodents. Large animal trials are planned next.

In the first experiments of this paper, Vagnozzi and others showed that the levels of TNNI3K in the heart increase after a heart attack. Measurements of TNNI3K protein levels failed to detect it in all tissue other than the heart. Furthermore, it was present throughout the heart, and mainly in heart muscle and not in blood vessels, fibroblasts, and other types of non-muscle heart tissues.

Next, Vagnozzi and others measured TNNI3K protein levels in heart transplant patients. The heart tissues of these patients, who had badly dysfunctional hearts showed higher than usual levels of TNNI3K protein. Thus, TNNI3K is associated with heart tissue and is up-regulated in response to heart dysfunction.

The next experiment examined the effects of overexpressing the human TNNI3K gene in mice. While the overexpression of TNNI3K did not affect heart function of structure under normal circumstances, under pathological conditions, however, this is not he case. If mice that overexpressed TNNI3K where given heart attacks and then “reperfused,” means that the blood vessel that was tied off to cause the heart attack was opened and blood flowed back into the infarcted area. In these cases, mice that overexpressed TNNI3K had a larger area of cell death in their hearts than their counterparts that did not overexpress TNNI3K. The reason for this increased cell death had to do with the compartment in the cell that generated most of the energy – the mitochondrion. TNNI3K causes the mitochondria in heart muscle cells to go haywire and kick out all kinds of reactive oxygen-containing molecules that damage cells.

Cell damage as a result of reactive oxygen-containing molecules (known as reactive oxygen species or ROS) activates a pathway in heart cells called the “p38” pathway, which leads to programmed cell death.

p38 signaling

Once Vagnozzi and his colleagues nailed down the function of TNNI3K in heart muscle cells after a heart attack, they deleted the gene that encodes TNNI3K and gave those TNNI3K-deficient mice heart attacks. Interestingly enough, after a heart attack, TNNI3K-deficient mice showed much small dead areas than normal mice. Also, the levels of the other mediators of TNNI3K-induced cell death (e.g., oxygen-containing molecules, p38, ect.) were quite low. This confirms the earlier observations that TNNI3K mediates the death of heart muscle cells after a heart attack, and inhibiting TNNI3K activity decreases the deleterious effects of a heart attack.

And now for the pièce de résistance – Vagnozzi and his crew synthesized small molecules that inhibited TNNI3K in the test tube. Then they gave mice heart attacks and injected these molecules into the bellies of the mice. Not only were the infarcts, or areas of dead heart muscle cells small in the mice injected with these TNNI3K inhibitors, but the heart of these same mice did not undergo remodeling and did not enlarge, showed reduced scarring, and better ventricular function. This is a proof-of-principle that inhibiting TNNI3K can reduce the pathological effects of a heart attack.

This strategy must be tested in large animals before it can move to human trials, but the strategy seems sound at this point, and it may revolutionize the treatment of heart attack patients.