Last week I started a really exciting experiment using a skin biopsy…! For any experiments using human samples, scientists have to seek approval first from an ethics committee to ensure that volunteers, samples and data will all be handled correctly or ‘ethically’. For even a small saliva sample, ethics approval is necessary before carrying out any work and approval usually takes weeks to be granted. I first submitted my ethics application back in January and after a few revisions, it finally got accepted in March! Since then we’ve took some time to send emails to recruit volunteers and then arrange for sample collection at the hospital.
Getting my first sample was both an exciting experience and an anxious one… I was looking forward to getting stuck into bench work again, but at the same time, this was my first experience of working with human tissue. In my previous lab I had worked with human cell lines that were derived from cancer patients and are immortalised. This means that they will grow indefinitely and are usually quite easy to keep happy. These cells tend to grow at a nice rate, and only require tending to every 2-3 days which meant that I could keep in a good routine with them. But I had no idea how cells from the human tissue would grow. Of course I’ve done my reading and spoken to others that have worked with similar types of cell, but it’s never the same as handling them yourself and getting used to how they look and behave.
Once I had received the sample I had to transport it back to the university campus; luckily that’s only a 10-15 minute walk from the hospital so I didn’t have to travel far. Once back in the lab I had to separate the two layers of the skin as I am interested in cells that are in both the epidermis and dermis. I minced the layers individually using two scalpel blades and then added the tissue pieces to tubes containing an enzyme called trypsin. Trypsin is a type of protease enzyme that breaks down proteins and helps the individual cells to separate out from the tissue. This tissue digestion is a really important step because you need to make sure the tissue is digested enough to release the cells, but also not over-digested and kill the cells.
After the digestion, I washed the pieces of tissue with a salt solution to remove any residual enzyme and then transferred the pieces into flasks for growing. The media that the tissue pieces are grown in contains all of the nutrients that they need to grow and some antibiotics to prevent any unwanted bacteria growing too.
The experiments that I want to carry out will require a few million cells so I am continuing to grow them in the flask, changing the media regularly to make sure they don’t run out of any nutrients that they need. When the cells fill the entire plate they are described as being 100% confluent and I will then have enough cells for the experiments.
The above picture shows what my isolating cells look like at the moment (blue arrows). Their growth is slow, but they have been under some stress adjusting to these new conditions outside of the human body and so that is always to be expected to begin with. I’m really looking forward to seeing what these cells could tell me in a couple of weeks!