Stories about: mitochondria

Hearts get a boost from mitochondrial transplantation

In this artistic rendering, mitochondria (enlarged at top left) are depicted inside heart muscle cells. Watch an animation about mitochondrial transplantation.

For decades, cardiac researcher James McCully, PhD, has been spellbound by the idea of using mitochondria, the “batteries” of the body’s cells, as a therapy to boost heart function. Finally, a clinical trial at Boston Children’s Hospital is bringing his vision — a therapy called mitochondrial transplantation — to life.

Mitochondria, small structures inside all of our cells, synthesize the essential energy that our cells need to function. In the field of cardiac surgery, a well-known condition called ischemia often damages mitochondria and its mitochondrial DNA inside the heart’s muscle cells, causing the heart to weaken and pump blood less efficiently. Ischemia, a condition of reduced or restricted blood flow, can be caused by congenital heart defects, coronary artery disease and cardiac arrest.

For the smallest and most vulnerable patients who are born with severe heart defects, a heart-lung bypass machine called extracorporeal membrane oxygenation (ECMO) can help restore blood flow and oxygenation to the heart. But even after blood flow has returned, the mitochondria and their DNA remain damaged.

“In the very young and the very old, especially, their hearts are not able to bounce back,” says McCully.

Ischemia can be fatal for the tiniest patients

After cardiac arrest, for instance, a child’s mortality rate jumps to above 40 percent because of ischemia’s effects on mitochondria. If a child’s heart is too weak to function without the support of ECMO, his or her risk of dying increases each additional day spent connected to the machine.

But what if healthy mitochondria could come to the rescue and replace the damaged ones?

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Maintaining mitochondria in neurons: A new lens for neurodegenerative disorders

cartoon of mitochondria being transported in neurons - part of mitostasis
In some neurons, mitochondria must travel several feet along an axon. (Elena Hartley illustration)

Tom Schwarz, PhD, is a neuroscientist at Boston Children’s Hospital’s F.M. Kirby Neurobiology Center, focusing on the cell biology of neurons. Tess Joosse is a biology major at Oberlin College. This article is condensed from a recent review article by Schwarz and Thomas Misgeld (Technical University of Munich).

Like all cells, the neurons of our nervous system depend on mitochondria to generate energy. Mitochondria need constant rejuvenation and turnover, and that’s especially true in neurons because of their high energy needs for signaling and “firing.” Mitochondria are especially abundant at presynaptic sites — the tips of axons that form synapses or junctions with other neurons and release neurotransmitters.

But the process of maintaining mitochondrial number and quality, known as mitostasis, also poses particular challenges in neurons. Increasingly, mitostasis is providing a helpful lens for understanding neurodegenerative disorders. Problems with mitostasis are implicated in Parkinson’s disease, Alzheimer’s disease, ALS, autism, stroke, multiple sclerosis, hypoxia and more.

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Science and medicine in 2018: What’s the forecast?

2018 predictions for biomedicine

Vector consulted its many informants to find out which way the wind will blow in 2018. Here are their predictions for what to expect in genetics, stem cell research, immunology and more.

GENETICS

Gene-based therapies mature

We will continue to see successes in 2018 reflecting the maturation of gene therapy as a viable, generalizable platform for curing many rare diseases. Also, we will see exciting new applications of other maturing platforms, like CRISPR/Cas9 gene editing and oligonucleotide therapies for neurologic diseases, building on the success of nusinersen for spinal muscular atrophy.

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Monitoring mitochondria: Laser device tells whether oxygen is sufficient

Shining a laser-based device on a tissue or organ may someday allow doctors to assess whether it’s getting enough oxygen, a team reports today in the journal Science Translational Medicine.

Placed near the heart, the device can potentially predict life-threatening cardiac arrest in critically ill heart patients, according to tests in animal models. The technology was developed through a collaboration between Boston Children’s Hospital and device maker Pendar Technologies (Cambridge, Mass.).

“With current technologies, we cannot predict when a patient’s heart will stop,” says John Kheir, MD, of Boston Children’s Heart Center, who co-led the study. “We can examine heart function on the echocardiogram and measure blood pressure, but until the last second, the heart can compensate quite well for low oxygen conditions. Once cardiac arrest occurs, its consequences can be life-long, even when patients recover.”

In critically ill patients with compromised circulation or breathing, oxygen delivery is often impaired. The new device measures, in real time, whether enough oxygen is reaching the mitochondria, the organelles that provide cells with energy.

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