Thursday, February 26, 2015

How the “rejuvenation” process of Alex’s skin cells works

Alex: Now that you have grown all of these skin cells what’s next?

Lauren: We are going to turn your skin cells into stem cells. To make stem cells, we are using a technology called cellular reprogramming for which the Nobel Prize in Physiology/Medicine 2012 was awarded to Drs. Sir John Gurdon and Shinya Yamanaka. This ground-breaking discovery broke a central dogma of biology which basically stated that you cannot ‘turn the clock back’ or reverse the fate of a differentiated cell. Cellular differentiation refers to the developmental process of taking a cell from an undifferentiated or pluripotent state, e.g. stem cell, to a specialized state with specific function, e.g. skin, heart, liver.

Alex: How are you going to make stem cells from my skin cells?

Lauren: We are introducing four different proteins delivered by a virus into your skin cells. The proteins force and "remodel" your skin cells and turn them into stem-cell like cells that we call induced pluripotent stem cells or "iPS" cells. A scheme of the process is shown in the image below. iPS cells share similar qualities to embryonic stem cells, they can divide almost indefinitely in the culture dish, that means practically, you can grow them continuously for years. iPS cells also have the characteristic to differentiate into any cell or tissue type of the human body.


Alex: What is your ultimate goal? What do you want to do with my cells?

Birgitt: We want to find out why you got Parkinson’s disease and why your dopaminergic neurons in your brain are dying. We think we can do this in this individualized or personalized approach by making your stem cells differentiate into your dopamine producing nerve cells. Then we can compare them to healthy control cultures and define differences and changes. Once we know why your dopaminergic neurons are susceptible, they can be tested with known or novel compounds that potentially reverse the changes and restore them to their normal function. This is the long-term goal, but we will explain in this blog how we build the cell model from your skin cells.


Alex: You make it sound so simple and easy, but I am sure there is more behind the scenes.

Birgitt: There are definitely additional hurdles and challenges to overcome, but the concept works and the model has obvious advantages -using cells from someone who has the disease- over the traditional cancer cell models that have been used for the last few decades. If you are interested in more details, background and stem cell news, here are some links and blogs.

Thursday, February 12, 2015

Alex’s cells growing out of their “clothes”

Alex: I miss seeing my cells. How are they doing?

Birgitt: In the last two weeks your cells have grown a lot. In the image below you can see your skin fibroblasts at a low density. When you watch the cells carefully under the microscope, you can see cells are dividing. I have drawn some arrows that point to these pairs. How many more dividing cells can you find in this picture?


Alex: 1, 2, 3 maybe…more?

Birgitt: To witness how cells grow is always fascinating, isn’t it? In the next two images you can compare your cells on day 20 and day 22 after biopsy. Within two days all the space between the cells is filled up. Once the fibroblasts become dense and touch their growth slows down which is called contact inhibition.

Day 20
Day 22

Alex: What do you do when the cells in the culture dish become overcrowded. You explained last time that you “split” the cells. How does that work?

Birgitt: In order to split the cells, we use trypsin which is an enzyme also found in your digestive system that breaks down proteins. The trypsin treatment is only needed for a few minutes. During that time the cells lift off the culture dish, then they are washed to remove the trypsin, transferred to a larger culture vessel, and replenished with fresh media. During the expansion period, I expand the cells from the original culture dish with a surface area of about 45cm2 to three large flasks with a total surface area of 450cm2 as you can see in the image below.

Alex: Wow that is a 10-fold expansion. How many cells will you have grown at the end?

Birgitt: In these three flasks are about 20 million of your skin cells. I will freeze them in special hibernation media in little vials at 1 million cells per vial. This stock of your skin cells is the foundation for all downstream experiments. Now, we can start planning the next phase: turning your skin cells into induced pluripotent stem cells, a process called nuclear reprogramming.

Alex: Very excited to learn about it. Thank you.