Blood from young adults is being trialled as a treatment for Parkinson鈥檚 disease by a firm that wants to use the therapy to target neurodegenerative conditions.
Alkahest, a firm co-founded by聽Tony Wyss-Coray of Stanford University, California, has already tested blood-based treatments in people with Alzheimer鈥檚 disease. In the latest trial, 90 people with聽Parkinson鈥檚 鈥� mostly in their聽70s聽and 80s 鈥� will receive injections five days in a row, and then again three months later. Tests will determine whether the聽treatment improves their memory, attention, language skills or other cognitive abilities.
The trial is inspired by research by Wyss-Coray and others at Stanford University showing that cognitive declines in old mice can聽be reversed by giving them injections of blood from young mice. Since this discovery, Wyss-Coray has been trying to work out precisely what it is in young blood that drives this anti-ageing effect.
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He and his team have spent the past few years injecting different extracts from young human blood into old mice to see which have the most restorative effects. They haven鈥檛 specifically sourced blood from young people, but are聽using blood from collection banks whose overall average donor age is 32.
Although we don鈥檛 yet know why young blood may be rejuvenating, one idea is that younger bodies make restorative proteins that older bodies don鈥檛.
Wyss-Coray鈥檚 experiments have indicated that a certain 鈥渇raction鈥� of young blood聽鈥� a mixture of about 1000 different proteins聽鈥� has particularly powerful effects. After old mice were injected with this fraction, they performed as well as young mice in cognitive tests, grew new brain cells and had聽less brain inflammation, says Alkahest CEO Karoly Nikolich. 鈥淲e聽believe it contains the majority of beneficial proteins that are responsible for cognitive improvements,鈥� he says.
If the firm is right, this approach may prove more successful than earlier trials, which simply used blood plasma transfusions in an effort to relieve mild-to-moderate Alzheimer鈥檚 disease. in 18 people last year hinted at small cognitive improvements, but the study was too short and too small to know for sure if the treatment worked.
In April 2018, Alkahest began a larger trial in people with mild-to-moderate Alzheimer鈥檚, this time giving them just the fraction of blood it believes has the most rejuvenating effects. It is now beginning to give this fraction of blood to people with Parkinson鈥檚, and hopes to begin trialling the same blood extract in people with severe Alzheimer鈥檚 disease soon.
Mystery molecules
The researchers still don鈥檛 know which of the 1000 proteins in the fraction are responsible for the mental improvements seen in old mice, or how they work, but they are now testing them one by one to find out.
The blood fraction may contain聽proteins that indirectly rejuvenate the brain by boosting the immune system, says Michal Schwartz at the Weizmann Institute of Science in Israel. 鈥淲e now know that communication between the brain and immune system is pivotal for brain function, and that this communication seems to dysfunction in ageing and Alzheimer鈥檚,鈥� she says.
Alkahest hopes to identify the聽protein or group of proteins responsible for the therapeutic effects so synthetic versions can be made in the lab, instead of having to be isolated from donor blood, says Nikolich.
This would be a major advantage as donor blood is in limited supply, says David Irving at the Australian Red Cross Blood聽Service. People receiving young blood for Alzheimer鈥檚 or Parkinson鈥檚 would need regular transfusions, since the beneficial proteins are likely to break down聽over time, he says. 鈥淭here certainly wouldn鈥檛 be enough to go around if it was used for all patients with these conditions.鈥�
However, it may be tough to make the therapeutic agent, says Lorna Harries at the University of Exeter in the UK. 鈥淚t is probably a complicated mix of things that might be difficult to replicate synthetically,鈥� she says.
It is unusual for a treatment to聽progress to clinical trials before聽its mechanism of action is聽understood, says Irving. But the聽blood fraction is likely to be safe, since the safety of blood transfusions is well established, and there is an urgent need for Alzheimer鈥檚 and Parkinson鈥檚 treatments, he says.
