Infections of the hair follicles can be challenging to treat because bacteria tend to settle in the space between hair and skin, making it hard for treatments to reach them. To study this issue more thoroughly in a lab setting, researchers from the Department of Drug Delivery Across Biological Barriers at the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) have created an innovative model. This model incorporates human hair follicles embedded in a 3D-printed matrix. It aims to facilitate the assessment of new drug candidates against specific pathogens directly on human hair follicles. The findings have been published in the journal ACS Biomaterials Science & Engineering.
Hair follicles are intricate structures that not only anchor the hair root to the skin but also create a prime environment for microorganisms to thrive. This can lead to persistent inflammation, which is painful and, in severe cases such as with acne inversa, may lead to secondary conditions like diabetes mellitus or acute sepsis. Currently, around 830,000 individuals in Germany are dealing with this issue.
To effectively create new treatments for hair follicle inflammation, models that closely mimic the skin’s physiological conditions in a laboratory are required. A research team led by Prof. Claus-Michael Lehr at HIPS, in collaboration with Saarland University, has successfully developed such a model. They achieved this by transplanting living human hair follicles into a collagen matrix supported by a 3D-printed polymer framework, effectively recreating the natural surrounding of hair follicles. “This model allows us to evaluate new drug candidates in the hair follicle’s microenvironment at an early development phase, eliminating the need for animal testing,” explains Samy Aliyazdi, the lead author of the study.
In the past, new drugs targeting hair follicle infections were tested in simpler setups, like human hair follicles floating freely in a liquid culture. However, these setups failed to accurately reflect the actual conditions found in patients, making them less than ideal for evaluating biological efficacy. Through the novel 3D model, researchers have demonstrated that nanoparticles can penetrate and spread more effectively in hair follicles compared to those in simple floating cultures. Consequently, nanoparticles can reach deeper into the follicles, acting as effective delivery systems for active ingredients. The research team also discovered that hair follicle infections due to the hospital pathogen Staphylococcus aureus can be treated much more effectively when the antibiotic rifampicin is encapsulated within these nanoparticles.
The new 3D model of human hair follicles addresses several limitations found in previous models used in laboratories. “Our model offers a more authentic representation of the human hair follicle microenvironment and allows for extended culture periods. However, we still have more work ahead. We need to enhance the mechanical properties of the polymer and plan to introduce additional cell types like fibroblasts and immune cells to make the model even more representative of actual patient conditions,” Aliyazdi states. Such an advanced model may provide crucial early insights into the health of hair follicles, pathogen behavior, and the predictability of drug effectiveness and safety evaluations. Lehr highlights, “Our work demonstrates that replicating the natural environment of hair follicles is essential for evaluating antibiotic efficacy. This model could greatly speed up the process of developing new, targeted therapies, all while reducing the number of necessary animal studies.”
