One of the more mysterious things doctors have ever seen
Is the spleen.
Throughout history
The function of the spleen has been shrouded in mystery.
The literature tells
It is known to filter blood, and remove dysfunctional red blood cells
It releases platelets and neutrophils when you bleed
And is a source of stem cells, in times of need
It can produce new red blood cells, like the marrow
But its function is not that narrow
Today, we see excellent news from drug trials (phase one)
For people with Type 1 Diabetes, which is not fun.
Mass General is testing the Calmette-Guerin vaccination
In a new situation;
It has been used to prevent tuberculosis and in the treatment of bladder cancer
But now there are questions about diabetes for which it might be the answer
The first trials show it is safe to use
Which is good news
And it has been shown to reverse type 1 diabetes in mice
Which is very nice
Even if you don’t happen to be a mouse
Which, as it happens, is the case for all the diabetics in this house.
So now, Phase II trials are beginning
And, though it is too early to really say that we are winning
I think I can reasonably say
It’s a good day.
According to their press release, the Phase I trials showed no ill effects of Calmette-Guerin vaccination on individuals with type 1 diabetes. This is not really unexpected; the C-G vaccine is already in use for TB and for bladder cancer, so it has had to pass such tests before. The big news is both in the past and in the future. In the past, this vaccine has allowed mice with type 1 diabetes to reverse the course of their disease. Studies have shown that the vaccine stimulates splenic stem cells to produce pancreatic islet cells; the stem cells essentially mimic their function in embryogenesis. In the future, the therapeutic potential for these stem cells is promising–not just for type 1 diabetics, but hey, right now that’s the application that’s got me smiling.
I’d try to explain the process a bit more, but it is not my area, so I’ll defer to any of my readers who have the expertise–or if you see that someone else has written about it, let me know!
Someone recommended this blog to me and so far I’m impressed. I’ve put you on my blog roll.The impression I get from these articles and a couple of others on PubMed is that the vaccine doesn’t directly stimulating splenic stem cells. The theorised mechanism seems to be:Patient recieves BCG vaccineBCG vaccine increases levels of one of the chemicals which regulate the immune system (TNF-α)TNF-α decreases the activity of the group of immune cells responsible for attacking insulin producing islet cellsThe stem cells can then differentiate into functional insulin secreting cells without being under constant attack by the immune system. Thus pancreatic insulin secretion is restored.(I’m definitely not an expert though, so if someone comes along with a different explanation listen to them instead)
Thanks, rhyming med student! (wait… a rhyming med student? I must check out your site!)I also wanted to check–is it your understanding that the new islet cells are actually in the spleen (at least some) rather than the pancreas? Or is it both? Or am I just wrong?
I'm normally a pretty deep lurker, but I wanted to come out to say two things.1.) Your ability to make any subject into a rhyming poem amazes me every single time. It's incredible.2.) This is wonderful news, thank you. Most of the men on my father's side of the family had diabetes, and although it's too late for my dad, grandfather, uncles, and cousins, I'm hopeful for my nephews/second cousins, and any sons I may have.I very much enjoy your blog.
Wow. That is good news. And in verse!
The transfused splenic stem cells generate new islets mainly (probably entirely) in the pancreas.The only study I found that specifically examined the spleen after treatment didn't find any changes. That study was focussed on slowing diabetes progression rather than regenerating islets though, so the treatment protocol was different (no BCG, different quantity of stem cells infused, etc) and the observation period was a bit shorter.