One of the saddest things about being diagnosed with breast cancer a few years ago (it was fortunately treatable) was having to stop breastfeeding my 10-month-old baby. Unceremoniously she was shunted on to an early diet of pure solid food, which I reasoned was probably just as nutritious as infant formula and the best solution in the absence of donor milk from a breast-milk bank, which is reserved for premature and ill babies, and dispensed by prescription.
Baby Agnes thrived, but what if there were another option? What if we could make human breast milk in the lab? Enter startups Biomilq and TurtleTree Labs, founded in 2019 and based in the US (North Carolina) and Singapore respectively. The companies believe they can provide a more nutritious alternative to infant formula by inducing human mammary cells in a bioreactor to lactate, then harvesting the product. “The end goal is a product that is as close to breast milk as we can produce,” says Michelle Egger, Biomilq’s co-founder and CEO.
Lab-made milk has similarities with lab-grown meat. While the cultivated meat companies are trying to grow animal cells that can then be harvested and eaten, milk companies aim to keep human mammary cells healthy and fed so they will secrete milk.
This June, Biomilq secured $3.5m and TurtleTree Labs $3.2m in early investment. Bill Gates’s venture firm is among Biomilq’s funders, while backers of TurtleTree Labs include the venture firm of the Saudi prince Khaled bin Alwaleed bin Talal. TurtleTree Labs says its methods could also be applied to producing the milk of other mammals; cow milk is a second area of work.
Both companies acknowledge that their products can’t replicate everything in breast milk. They won’t, for example, include the antibodies a mother’s milk contains, which help a baby fight infection and protect against allergies, or the microbes known to help infant gut health. But they believe that they can trigger the cells to produce thousands of the components found in breast milk. These include proteins, fats and the entire spectrum of human milk oligosaccharides (HMOs), complex sugars that nourish young immune systems. Nothing is yet on the market and the work is still at an experimental stage.
“Visually you can see that milk has been produced,” says Fengru Lin, TurtleTree Labs co-founder and CEO, adding that the colour is whitish and the nutritional quality is similar to human breast milk.
Tests so far, Egger says, have confirmed that the cells are producing lactose, the sugar found naturally in most mammals’ milk, and human casein. She expects further testing to reveal other components. If proven, the technology would leapfrog the best efforts to improve cow-based infant formula: adding one or two key HMOs made by bio-engineering microbes.
The concept of inducing mammary cells in a dish to lactate is not new. Over the past couple of decades, scientists have had success plying 3D clusters of animal and human mammary epithelial cells with lactogenic hormones. But that was to study mammary-gland biology – not to make milk in an industrial sense.
“No one was thinking of using this as a production system,” says Bruce German, director of the Foods for Health Institute at the University of California, Davis, who studies breast milk and has provided unpaid advice to Biomilq. Experiments published to date have shown the production of some milk proteins – casein and whey protein – and lactose. “[But] the full spectrum of what I would define as milk definitely hasn’t been achieved,” notes Alecia-Jane Twigger, a lactation and mammary gland biologist at the University of Cambridge. It isn’t even known how the mammary gland makes all the thousands of different components it does, she adds.
Biomilq begins with adult mammary cells, which it says are predominantly epithelial cells, found in the ducts and lobules of the breast. TurtleTree Labs starts with stem cells, which it induces to grow into mammary cells. Both say their secret is in their culture media – the fluid containing nutrients, vitamins, and lactation hormones they feed their cells. They also say they have their own unique bioreactor systems, which allow their milk to be harvested free of cells, media and waste.
TurtleTree Labs’ vision is to license its technology to infant formula manufacturers. Biomilq has been considering whether it could extract mammary cells from women before their babies are born, and then produce milk from those mammary cells to create a personalised milk – though individualisation would be lost too: maternal diet, for example, influences breast milk.
Both say their goal is an affordable product, though cell-culture media can be expensive, notes Twigger. Egger aims to be on par with top-end infant formula. Max Rye, TurtleTree Labs co-founder and chief strategist, says the company was producing a litre for around $170 (£127) but has managed to lower the cost to $35 (£26) by synthesising components of the lactation media in-house. The price of a litre of ready-to-drink infant formula is about $8 in the US and £4 in the UK.
The companies are yet to present any scientific data to support their claims. “They have gone after one of the most difficult biological challenges there is,” says German. To show that they are producing something that “even vaguely resembles milk”, Twigger says she would like, as a start, to see proof of different species of HMOs and fats.
Even if the companies can get that far, there will still be much absent from a bulk milk tank. And that extends beyond breast milk’s immunological properties. The production of breast milk is a dynamic process. It changes not only over the course of a breastfeeding term but also over an individual feeding, and even with the time of day. Biotechnology is no match for the human breast. “Mothers should feel special,” says German, adding that breastfeeding is also associated with health benefits for mothers.
Achieving industrial-scale production is also unlikely to be easy. The scientific research has seen only microlitres produced, says Twigger, and she hasn’t seen evidence that mammary cells in the lab can sustain production for more than a few weeks. The companies will also face hurdles in gaining approval for their products.
Egger says Biomilq is focused on testing and isn’t looking to launch anything yet. Rye says TurtleTree Labs is continuing to iterate and is planning to sign its first licensing agreement by mid-2021. Neither seems fazed by the task of scaling up, and both are looking into the path to regulation. “That we don’t have antibodies and microbes turns out to be a huge advantage,” says Rye.
The technology could be controversial. On one hand many women struggle to breastfeed. The infant formula they have to fall back on is “basically the barest essentials,” says German. On the other, if lab milk reduces the chances of women breastfeeding it is likely to rile some doctors and breastfeeding groups.
“There is a need for a high-quality breast-milk substitute for those infants who are not breastfed,” said the breastfeeding support charity, La Leche League Great Britain. But the charity also asked whether similar investments to those being ploughed into the technology shouldn’t be put towards supporting women who want to breastfeed. La Leche also emphasised the “artificial” nature of the proposed products. “The benefits of breastfeeding cannot be replicated in a laboratory,” it said.
For their part, the companies emphasise that their aim isn’t to replace breast milk, breastfeeding or breast-milk banks, but simply to be the next best thing if that isn’t possible. “Babies deserve whatever we can do to get them the best nutrition,” says Egger. “Technology has changed and it is time we started to apply some of that in honour of babies, mums and families.”