New Immune Cells Found in Mother's Milk

It's well-known that breastfed babies tend to be healthier than babies given a bottle filled with formula, especially in their first year of life, and the benefits are numerous. What's more, the longer a baby is breastfed, the more far-reaching the health effects are throughout their lives.

The developing field of stem cell biology is being used by scientists to differentiate the types of cells derived from breast milk. While there are innumerable studies on the advantages mothers offer their children when they choose to breastfeed, one discovery in the last decade concerns the millions of immune cells known as innate lymphoid cells, or ILCs. According to a JAMA Pediatrics study published in 2018:

"Innate lymphoid cells (ILCs), a new class of lineage-negative lymphoid cells, are key to intestinal microbiome and the adaptive immunity of the infant. Innate lymphoid cells have been classically divided into 3 subgroups of ILC1s, ILC2s, and ILC3s, based on their cytokine secretion and transcription factor profiles."¹

For the above research, scientists conducted extensive cell analysis on fresh milk from four lactating women and found that ILCs can influence not just babies' immune systems, but fight inflammation and improve tissue health.

ILCs may protect breastfeeding moms from getting an infection from their babies and possibly enable a change in the content of the breast milk to help the baby get over such an infection, as well. Further, scientists say some immune cells, such as leucocytes, which are white blood cells that fight infection, increase in breast milk in response to infections in babies.²

Breast Milk Differs Depending on Mother's Weight

Another recent study shows that the breast milk from normal weight mothers is different from that of overweight mothers.³ In addition, variations in small molecule metabolites found in breast milk could increase the risk factors for childhood obesity. The study, from Joslin Diabetes Center, was quite telling:

"The aim was to identify the molecular features of breast milk according to the mother's weight status (normal versus overweight/obese) and then to determine if any differences predicted excess weight in the first months of the infant's life.

At one month of age, 10 metabolites were found that differentiated overweight/obese mothers from lean mothers. Of those, four were identified as nucleotide derivatives and three were identified as complex carbohydrates called oligosaccharides, which may alter the gut microbiota.

At six months of age, the analysis revealed that 20 metabolites differed in overweight versus lean women. Additionally, milk adenine in obese mothers was associated with greater weight gain in infants."⁴

New Research: Breast Milk and Progress in Stem Cell Biology

The journal Human Cell published a study in April 2019 that involved researchers from Russia and one from the U.K. It noted that studies continue to provide information about "purification, propagation and differentiation of certain types of progenitor cells from breast milk,"⁵ the possible fate of those cells and the fact that they exhibit many properties typical of stem cells.

Much more than mere nutrition is bequeathed to babies who are breastfed. They're also supplied with specially balanced essential nutrients and "functionally distinct bioactive components"⁶ crucial to the health and well-being of newborns and older babies. One important aspect is that breastfeeding lowers their risk and susceptibility of infection.⁷

Breastfeeding also supplies infants with a complex combination of nutrients directly from their mothers' immune cells, while at the same time supporting, regulating and adapting the babies' own immune systems. Cells that are essential to health pass through their gastrointestinal tracts and colonize in optimal numbers in their spleens, livers and lymph nodes.⁸ Additionally:

"Communication between breast milk components and their natural host, the infant, which create a symbiotic commensal relationship, have allowed some researchers to suggest that the breast milk is a live system and could even be considered an organ."⁹

Breast milk has extraordinary influences on the health of infants who receive it as a steady diet. One of the most dramatic is the rapid cell response while they're being fed. However, every aspect of how each baby's immediate needs is fulfilled is presently unknown. One study suggests human breast milk could be considered a probiotic food.¹⁰ Another study shows that:

"(Human) milk has the consistent function of providing nourishment, protection, and developmental programming to the young, with short- and long-term effects. Among its components that confer these functions, breast milk contains maternal cells, from leukocytes to epithelial cells of various developmental stages that include stem cells, progenitor cells, lactocytes, and myoepithelial cells."¹¹

Leukocytes are part of your body's immune system that help fight infection and disease. Epithelial tissue, which covers all the exposed surfaces of the body, helps protect against many harmful factors, including pathogens.¹²

Unique Properties of Breast Milk-Derived Stem Cells

An Australian study shows that stem cells from breast milk have abnormally low potential for becoming tumorigenic, and their ability to form teratomas — a type of germ cell tumor that can comprise several different types of tissue, such as bone, hair and muscle — is small.¹³ The study concludes:

"These findings provide evidence that breast milk represents a novel and noninvasive source of patient-specific stem cells with multilineage potential and establish a method for expansion of these cells in culture.

They also highlight the potential of these cells to be used as novel models to understand adult stem cell plasticity and breast cancer, with potential use in bioengineering and tissue regeneration."¹⁴

A Canadian study reported in 2017 that breastfeeding prevents necrotizing enterocolitis (NEC), a devastating disease affecting mostly premature infants when their intestinal walls are "invaded by bacteria, which cause local infection and inflammation that can ultimately destroy the wall of the bowel."¹⁵

However, the study further shows that exosomes (the cellular components or vesicles on the outside of a cell) purified from breast milk are able to promote intestinal epithelial cell growth, such as the viability, proliferation and activity of stem cells in infants even when they are formula feeding.¹⁶

The study concludes, "These findings provide insight into the mechanism of action of breast milk in the intestines. Exosome administration is a promising prevention method for infants at risk of developing NEC when breastfeeding is not tolerated."

History of Breastfeeding (or Not) and the Sobering Results

Breastfeeding is acknowledged as an indispensable part of childbirth, or was until alternatives to breastfeeding began, reportedly as early as 2000 BC, and more so when infant formula was invented. Alternatives for the health-optimal practice of breastfeeding have taken several avenues, including wet nursing, use of cow's milk and formula use, according to a report, "A History of Infant Feeding," which states:

"In the 1920s, scientists also began developing nonmilk-based formulas for infants allergic to cow's milk. The first nonmilk formula was based on soy flour and became available to the public in 1929. Like the first formulas introduced in the late 19th century, soy formula lacked vital nutrients, particularly vitamins. Eventually, the problem was resolved with vitamin fortification.

As formulas evolved and research supported their efficacy, manufacturers began to advertise directly to physicians … By the 1940s and 1950s, physicians and consumers regarded the use of formula as a well-known, popular, and safe substitute for breast milk. Consequently, breastfeeding experienced a steady decline until the 1970s."¹⁷

In the 1970s, breastfeeding was promoted again, according to the report, but in 1988, the formula industry started marketing directly to the public, which again resulted in a decrease in breastfeeding across the U.S. Later studies revealed positive outcomes for breastfed babies — and negatives for formula-fed babies — in three specific areas:

• Atopy — The condition was characterized as hypersensitivity or an allergic reaction such as eczema, asthma and allergic reactions to food,¹⁸ with "asthma exacerbations accounting for 50% of all emergency hospital visits,"¹⁹ which "significantly reduces the quality of life in young children."²⁰
• Diabetes mellitus — "Short duration of breastfeeding and an early introduction of cow's milk may trigger pancreatic beta-cell autoimmunity, resulting in Type 1 diabetes."^21,22 Breastfeeding may also reduce childhood obesity, helping to prevent Type 2 diabetes.²³
• Childhood obesity — Breastfeeding reduced obesity, while obesity in formula-fed infants was far more prevalent.²⁴ Additionally, infants breastfed over a longer period of time, such as several months, were found to have the lowest risk of being overweight as an adolescent.²⁵

The serious consequences and illnesses seen today in the U.S. are a result of the decreasing number of breastfed babies in the 21st century. The history study concluded that breastfeeding is best:

"Research suggests that breastfeeding prevents adverse health conditions, whereas formula-feeding is linked with their development. This evidence confirms breastfeeding is still the best source of infant nutrition and the safest method of infant feeding."²⁶

ILCs: 'Like a Central Command With No Soldiers'

There are several types of ILCs residing in the tissues of babies as they develop, but they appear "stationary and inactive, waiting for a developed immune system to communicate with," says Babak Baban, an immunologist in the oral biology department at the Dental College of Georgia at Augusta.²⁷

The cells remain "upstream" in readiness to initiate and advance an immune response when needed, he adds. "Until then, these cells are like a central command in each tissue with no soldiers."

However, rather than ILCs attacking pathogens directly, they send cytokines to tell the most abundant immune cells, called macrophages, to handle it.²⁸ According to Science Daily, which summarized the JAMA article (which is behind a pay wall):

"Macrophages, which literally means 'big eaters,' are the largest of the white blood cells and much-better studied than ILCs. They are known for their ability to envelop unwanted items like bacteria, viruses and dead body tissue, and can also help incite or calm inflammation."²⁹

Of the three main types of ILCs transferred to babies through breast milk, scientists say type 1 is most prevalent. This ILC survives in the infant's gut for at least several days and not only protects against harmful bacteria, but helps form the basis for its own protective immune system.

'The Moment You're Born, You Start to Build a Microbiome'

According to Jack Yu, chief of pediatric plastic surgery at MCG, their research, which included mouse studies, found that ILCs begin helping to build your microbiome from the moment you're born. Baban, the study's corresponding author, adds that ILC3 specifically "helps form the protective mucosal layer for the gut and respond to the microbiome when it does develop."³⁰

Furthermore, Baban says breastfed babies have other frontline protection from immunoglobulin G, the most common antibody in our circulation, and the only one that transfers through the placenta to the baby.³¹

A breastfeeding advocate, Dr. Jatinder Bhatia also noted that rather than formula, donor breast milk is used in the neonatal unit of the Children's Hospital of Georgia when mother's milk is not available.

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