From Flat to Functional: Recreating Human Microbial Environments with 3D Bioprinting

 

Image: Bioprinting of 3D Convoluted Renal Proximal Tubules on Perfusable Chips.Source: Homan K, Kolesky D, Skylar-Scott M, Herrmann J, Obuobi H, Moisan A, Lewis J (2016). "Bioprinting of 3D Convoluted Renal Proximal Tubules on Perfusable Chips". Scientific Reports. DOI:10.1038/srep34845

Not all microorganisms are harmful. In fact, our body naturally hosts tiny organisms like bacteria, viruses, and fungi that play essential roles in maintaining our health. Together, these helpful microbes make up what is known as the human microbiome. These beneficial bacteria and fungi aid in digestion, fight off harmful germs, and strengthen our immune system.

By Hannah Vargees 

Interestingly, these microbes don’t just interact with each other—they also interact closely with host tissues, immune cells, and environmental factors like pH levels, oxygen gradients, and nutrient availability within our body. Understanding these complex interactions is vital, especially when studying diseases or developing targeted therapies.

To study these interactions, scientists have traditionally relied on 2D cell cultures and animal models. But each of these approaches has its limitations.

First, let’s understand what 2D cell culture is. It involves growing human or animal cells on flat surfaces like plastic or glass dishes. These cells absorb nutrients from the surrounding media and spread out across the flat surface. While it’s a widely used and cost-effective technique, it doesn’t truly replicate how cells grow and behave in the human body. Flat growth alters cell behavior and signaling pathways, making it hard to recreate realistic tissue environments. Additionally, 2D cultures can’t support key features like biofilm formation or mucosal layering, both of which are essential for mimicking human microbial environments.

Next, we have animal models, which are commonly used to study diseases and drug responses. However, they come with their own challenges. There are species-level differences that are difficult to account for, and the immune responses in animals often differ from those in humans. This makes it challenging to translate findings directly into clinical outcomes, limiting their usefulness in drug development and microbiome studies.

This is where 3D bioprinting offers a promising solution. It allows scientists to precisely place cells in spatial arrangements that replicate tissue-like structures, enabling a more accurate and dynamic model of the human body. To create these structures, researchers use bioinks made from hydrogels like GelMA or alginate, which help simulate the natural tissue environment more effectively.

Hydrogels are particularly useful because they closely mimic the extracellular matrix (ECM) found in real tissues. They support cell growth, differentiation, and allow for the controlled diffusion of nutrients and oxygen. Moreover, they’re biocompatible and tunable, meaning they can be adjusted to match the mechanical and biochemical properties of specific tissues or organs.

In summary, while 2D cultures and animal models have laid the groundwork, 3D bioprinting is pushing the boundaries of how we study the microbiome and human health, offering more accurate, ethical, and customizable tools for modern research.

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)