RNA sequencing

Lab-grown human sperm cells could unlock treatments for infertility

/ Kevin McCormack / 1 Comment
Dr. Miles Wilkinson: Photo courtesy UCSD

Out of 100 couples in the US, around 12 or 13 will have trouble starting a family. In one third of those cases the problem is male infertility (one third is female infertility and the other third is a combination of factors). In the past treatment options for men were often limited. Now a new study out of the University of California San Diego (UCSD) could help lead to treatments to help these previously infertile men have children of their own.

The study, led by Dr. Miles Wilkinson of UCSD School of Medicine, targeted spermatogonial stem cells (SSCs), which are the cells that develop into sperm. In the past it was hard to isolate these SSCs from other cells in the testes. However, using a process called single cell RNA sequencing – which is like taking a photo of all the gene expression happening in one cell at a precise moment – the team were able to identify the SSCs.

In a news release Dr. Wilkinson, the senior author of the study, says this is a big advance on previous methods: “We think our approach — which is backed up by several techniques, including single-cell RNA-sequencing analysis — is a significant step toward bringing SSC therapy into the clinic.”

Identifying the SSCs was just the first step. Next the team wanted to find a way to be able to take those cells and grow and multiply them in the lab, an important step in having enough cells to be able to treat infertility.

So, they tested the cells in the lab and identified something called the AKT pathway, which controls cell division and survival. By blocking the AKT pathway they were able to keep the SSCs alive and growing for a month. Next they hope to build on the knowledge and expand the cells for even longer so they could be used in a clinical setting.

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Illustrations by Vishaala Wilkinson

The hope is that this could ultimately lead to treatments for men whose bodies don’t produce sperm cells, or enough sperms cells to make them fertile. It could also help children going through cancer therapy which can destroy their ability to have children of their own later in life. By taking sperm cells and freezing them, they could later be grown and expanded in the lab and injected back into the testes to restore sperm production.

The study is published in the journal Proceedings of the National Academy of Science.

New findings about muscle stem cells reveals the potential for growing replacement organs

/ Pallavi Penumetcha / Leave a comment

Chrissa Kioussi’s group at Oregon State University has made exciting advances in further unraveling the scientific mysteries of stem cells. In work detailed in Scientific Reports, this group found that muscle-specific stem cells actually have the ability to make multiple different cell types.

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Pumping up our knowledge about muscle stem cells

Initially, this group was interested in understanding how gene expression changes during embryonic development of skeletal muscle. To understand this process, they labeled muscle stem cells with a kind of fluorescent dye, called GFP, which allowed them to isolate these cells at different stages of development.  Once isolated, they determined what genes were being expressed by RNA sequencing. Surprisingly, they found that in addition to genes involved in muscle formation, they also identified activation of genes involved in the blood, nervous, immune and skeletal systems.

This work is particularly exciting, because it suggests the existence of stem cell “pockets,” or stem cells that are capable of not only making a specific cell type, but an entire organ system.

In a press release, Dr. Kioussi said:

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Chrissa Kioussi, PhD

“That cell populations can give rise to so many different cell types, we can use it at the development stage and allow it to become something else over time… We can identify these cells and be able to generate not one but four different organs from them — this is a prelude to making body parts in a lab.” 

This study is particularly exciting because it gives more credence to the idea that entire limbs can be reconstructed from a small group of stem cells. Such advances could have enormous meaning for individuals who have lost body parts due to amputation or disease.