A day in the lab of a cancer researcher: immunologist
The idea that our own immune system can be ‘boosted’ to increase its cancer fighting abilities excites scientists around the globe. This is called immunotherapy. Worldwide Cancer Research has been supporting immunotherapy research for over 15 years, and we continue to see an increasing number of applications for this area of research. This week we continue our day in the lab series with cancer immunologist Dr Frances Pearson.
8:00 It’s Monday morning and members of the Cancer Immunotherapies Group start to arrive for work. We greet each other and discuss what we did at the weekend. We prepare our meeting agenda, as Monday is Meeting Day. This is an important day of the week, when we have the chance to plan experiments for the rest of the week and share our recent results.
I quickly pop into the lab to check on the melanoma cancer cells that I am growing in plastic flasks in the incubator. They have expanded in number over the weekend. Later today I will ‘re-home’ them into new flasks, so that they have more room to keep dividing. In a few weeks, I will test whether the immune responses generated by our cancer vaccines are effective in killing these cells. They look happy and healthy for now, so I leave them be and join the group heading to the meeting room.
9:30 Kristen, our group leader, calls the meeting to order and asks if there is any housekeeping business. We discuss any issues with lab equipment, and what needs to be ordered for the next round of experiments. Then we talk about how we will make the most of the blood samples we will receive from our pool of regular healthy donors this week, making sure we maximise on all the cells we will have and share them out amongst the group. We discuss who will let Steph, our clinical research nurse, know how many samples we will need and when, and she will book appointments with the donors. On the day of the experiment they will visit the Mater hospital to have their blood taken, which we will collect and bring back to the lab.
It’s PhD student Kirsteen’s turn to give a presentation this week, and she tells us about her latest results. She has been working on a cancer vaccine, specifically targeting immune system cells called dendritic cells. These cells are the focus of our group’s work. They are key initiators of immune responses involved in detecting cancer cells and presenting them to the immune system in a form it can recognise. Our work aims to maximise the ability of certain types of dendritic cells to do this, in order to generate better immune responses that are more effective in killing tumours. ‘Immunotherapies’ such as these have significant potential for cancer treatment without the traumatic side effects of chemo- and radiotherapy.
After discussing her recent data, Kirsteen presents a recent publication in our field, and we all discuss its merits and its implications for our own research. Understanding how our data fits in with those of others who are also attempting to find treatments for cancer is a key part of developing our research.
Halfway through the presentation, our research assistant Ingrid gets a call and she steps outside to take it. This may not seem like polite meeting etiquette, but this call is important. It is to notify us that a baby has just been born at the Mater hospital, and the parents have donated the umbilical cord to the Queensland Cord Blood Bank, which has allocated it to us. Because our institute is part of the largest maternity hospital in the southern hemisphere, we are fortunate to receive a cord donation once or twice per week. Processing the cord must be prioritised over all other experiments, as the precious stem cells that are inside will begin to die as soon as they are removed from the baby. It’s a race against time to isolate the stem cells and freeze them down for safe storage.
11:00 After the meeting, Ingrid hops on the bus to the hospital to collect the cord, whilst PhD students Yoke Seng and Evie prepare the tubes and reagents needed to isolate the stem cells from the blood. You may be wondering why these stem cells are so precious to us. Stem cells are early in development, and so have the ability to develop into many different kinds of cells, including immune cells. One of the tools we use to develop our cancer immunotherapies is the ‘humanised mouse’. We take a mouse that has been genetically modified to have no immune system of its own and transplant it with human cord stem cells. After a few weeks inside the mouse, these stem cells develop into a functional human immune system, with all the important cells that are involved in the processes of recognising and killing cancer cells. This makes it an almost perfect ‘model’ of how the human immune system reacts to cancer, and allows us to test how we can boost the immune response using vaccines or other immunotherapies.
11:30 To access the stem cells we first need to remove all the blood cells we are not interested in, using a technique called density centrifugation. We put the cord blood into transparent tubes by carefully layering the blood onto a chemical called ficoll, capable of separating the blood into its constituent parts (photo A). Because this chemical has a different density to the blood, it doesn’t mix with the blood, but instead sits just underneath it. We put the tubes into a machine that spins them at high speed for 20 minutes. This will separate the blood cells into fractions, based on their size (photo B), with the smallest-sized cells at the bottom of the tube (e.g. red blood cells) and the larger-sized white blood cells at the top.
The white blood cell layer contains our stem cells, so we carefully transfer this white layer into another tube. Next we ‘label’ the stem cells within this white blood cell fraction using magnetic beads that bind to a molecule, called CD34, which is present only on stem cells. We run all the cells through a machine with a strong magnet that pulls out the CD34 bead-associated cells, which are moved into a fresh tube. We can freeze these highly pure stem cells for future use.
13:00 We have got to a part of the protocol where we can stop for lunch, as we are waiting for the cells to run through the magnetic isolation machine, so we head to the kitchen for a much needed break. Kirsteen is already there, and she tells us about how her day’s experiment is going.
She is testing a molecule she has recently made that will target a particular type of dendritic cell that we know produces good immune responses against cancer. The hope is that this molecule will help in the processing and presentation of cancer cells to the immune system (as shown in the top image, legend at bottom of page). The next step will be to vaccinate our humanised mice and analyse the immune responses generated. After that, we will establish human tumours in the vaccinated mice (using cells such as the melanoma cells I’m currently growing in the flasks) to see how well the immune system fights the cancer. If the tumours reduce in size over time, we will know that the immune cells we activated have been effective in killing off the cancer cells.
15:00 I leave the others to freeze the stem cells, and I return to my flasks of melanoma cells. These cells grow by sticking to the bottom of the flask. They are bathed in a liquid that provides them with all the nutrients they need to multiply. Firstly, I use a chemical that stops the cells from sticking to the flask, and then I count the cells to see how many I now have.
I work out that I need to ‘re-home’ the cells from each flask I have into three fresh flasks, to allow them more space and access to the liquid so they continue to multiply. Three days from now, I will repeat the process from these new flasks.
16:00 Next, I turn to one of my other projects. I am trying to create a virus that we will use to infect the stem cells so that they become more reactive to tumour cells before we transplant them into the mice. Then, over time, we will be able to track immune responses in the mouse, which have been generated by the vaccine. Today I will harvest the liquid from my ‘virus factory’ – a flask of cells that I added viral DNA to a few days ago. These cells have turned the DNA into virus particles, which they have now released into the liquid. I do a quick test to check that my virus is actually present in the liquid, and I am very happy to see that it is. I store it in the fridge for now, and replace the flasks in the incubator, at 37˚C, to let the factory get back to work.
17:00 I have finally finished lab work for today, and have cleaned down the equipment I have been using. I go into the office and catch up on paperwork and emails. I analyse the data from an experiment I carried out few days ago. An important part of each day is entering all the information about the day’s activities into my lab logbook. A printout of my data analysis is pasted in, and I write a paragraph to explain the results I obtained. This logbook is an important record and needs to be detailed enough for another person to repeat your experiment independently.
I prepare a list of tasks for tomorrow and leave it by my computer before shutting down and leaving for the day, satisfied in the knowledge that the progress we made today, and each day, contributes to the development of more effective cancer therapies that are so urgently needed.
Photo credits (cover photo and blood tubes): Dr Frances Pearson. “Our work is focussed on dendritic cells, stained using blue and green dyes in this image. They have the ability to ‘eat’ tumour cells (which can be seen in this image stained in red) and present parts of the tumour cells to the immune system so that it can recognise the tumour as a threat and mount a response against it.”
Dr Frances Pearson is a Worldwide Cancer Research-funded postdoctoral fellow in the laboratory of Dr Kristen Radford at the University of Queensland in Brisbane, Australia, where they are working to develop a new type of cancer vaccine.
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