macrophage stimulating protein and its contribution to hair growth
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Macrophage stimulating protein and its contribution to hair growth

Specific proteins and their effect on hair growth was studied in the Department of Dermatology, at Philipp University in Marburg, Germany, in 2004. Scientists Kevin McElwee, Andrea Huth, Sabine Kissling, and Rolf Hoffmann reported their success in discovering how Macrophage Stimulating Protein (MSP) contributes to hair growth from their research in the laboratory on human hair follicles and on mice.

The success of this study was due in part to previous successes by other scientists.

1. From a previous study by Lindner in 2000, hepatocyte growth factor (HGF) is a known promoter of hair follicle growth and development.
2. Other scientists had shown that another member of the HGF family with a similar protein structure is macrophage-stimulating protein (MSP).
3. Several studies by scientists Ronsin and Wang have concluded that HGF uses a cell receptor called MET and MSP uses a cell receptor called RON.
4. Though both HGF and MSP communicate with cells through different cell receptors, the different receptors can cause the cells to do similar things in response to activation.
5. Scientists Guadino, Quantin, and Thierry found that RON is used while people are still unborn to help develop bones, skin, lungs, and many other parts of our body.
6. The four scientists in this study found that MSP can be found in human hair.

Based on this previous information, that HGF is known to help hair grow and MSP and HGF are related, the scientists asked; therefore… can MSP also help hair grow? The effects of MSP on hair growth were evaluated with three studies.

Study 1

The first study they did was “ex vivo” which means they did not perform the study on a living subject but rather performed the study in a laboratory setting in a container. They used hair samples from five different volunteers. The hair follicles form each donor were separated into four groups and immersed in a nutrient rich solution to keep the hair follicles alive. One group of hair follicles was a control sample and the other 4 were exposed to increasing amounts of MSP: .01 ng, 1 ng, 10 ng, 100 ng per milliliter of nutrient solution. After 8 days, they observed an immediate increase in hair growth in the four hair samples that had been exposed to MSP compared to the hair growth in the control sample that did not get any MSP. Interestingly, the test with 1 ng per mL of MSP grew the most!

Study 2

The second study they did was “in vivo” which means “in life.” This time, they used living organisms to help them understand MSP and its relation to hair growth. Special beads were soaked in MSP and injected under the skin of 70 day-old mice. In eight mice they injected beads filled with 100 ng of MSP and in another eight mice they injected one microgram (10 times 100 ng) of MSP. As a control, they also put beads of saline into 8 additional mice in order to ensure that it wasn't the implantation of the beads that potentially caused hair growth, or that any hair growth detected was naturally occurring.

After 16 days, they observed the potential hair growth and this is what they found: All 8 mice receiving 1 microgram of MSP had hair growth at the site of the bead implant. 4 of the 8 mice with the 100 ng MSP bead had hair growth at the site of the bead. All 8 mice in the control group with saline beads had no hair growth, confirming that the beads themselves did not contribute to hair growth and that the additional hair growth in the other mice was not naturally occurring.

Study 3

This test was a longer-term “in vivo” test. More bead-implanted mice, and a control group, were used to discover the effect of MSP on hair growth for an extended period of time. Although they discovered some hair growth in this test, they found something more significant: The state of the follicles were in a “anagen” state, which means a period of growth, for al onger time period than would normally be expected compared to the control mice whose follicles were in a “telogen” state, which means a period of rest.

What conclusions did they draw?

1. MSP, like HGF can grow hair. Human MSP can successfully stimulate mouse hair growth.
2. MSP seems to be an important factor in hair growth. In test two, hair growth was first observed on day 16 in all mice exposed to MSP.
3. MSP, like HGF, seems to work the best at 1 ng in in vitro studies. A superior accelerated growth rate in human hair follicles was obtained with an MSP concentration in the range of 1 ng per mL, a concentration similar to that defined for ex vivo studies using HGF (discovered by scientists Jindo and Shimaoka).
4. MSP promotes an anagen state in hair follicles. The mice hair follicles located over beads with 1 microgram of MSP were in anagen state whereas adjacent skin contained telogen stage hair follicles. The control mice presented a uniform telogen hair follicle state.
5. The anagen state of hair can be prolonged by MSP. Implantation of beads soaked in MSP demonstrated that MSP can prolong the anagen growth phase of hair in young mice, complementing the results of ex vivo human hair follicle culture studies.
6. MSP can turn follicles from telogen to anagen state. Implantation of MSP soaked beads in mice with telogen stage hair follicles were could also create an an anagen growth state.
7. The use of MSP to grow hair has so far proven safe. Although MSP is known as a stimulator of cells, no apparent inflammation or hair follicle deformities at the site of bead implantation was observed.
8. The use of MSP to grow hair has no observable side effects. Other than the presence of the beads under the skin, and a hair growth response to MSP exposure, no other conditions were apparent in the skin of study mice.

Overall it seems that MSP is a naturally expressed product in hair follicles that promotes hair growth. Adding extra MSP to the MSP produced naturally further increases the growth of hair follicles.

Macrophage stimulating protein and its contribution to hair growth references

  • McElwee KJ, Huth A, Kissling S, Hoffmann R. Macrophage-stimulating protein promotes hair growth ex vivo and induces anagen from telogen stage hair follicles in vivo. J Invest Dermatol. 2004 Jul;123(1):34-40. PMID: 15191539
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