Earlier this year, bioscientists reported in the journal Acta Biomaterialia a novel way to 3D-print artificial human tissues to help heal bone and cartilage injuries. The innovative work was carried out by a team at Rice University’s Biomaterials Lab.
The team detailed their initial success at engineering scaffolds that can replicate the physical characteristics of osteochondral tissue, the hard bone beneath a compressible layer of cartilage that appears as the smooth surface on the ends of long bones. Common among athletes in particular, injuries to these bones can involve small cracks or pieces that break off and result in severe pain or lead to arthritis.
Historically, it has been difficult to reproduce this human material in the lab. The Biomaterials Lab team at Rice, in collaboration with researchers at the University of Maryland, discovered that the key to success is to mimic the tissue that turns gradually from cartilage (chondral tissue) at the surface to bone (osteo) underneath. They did this by printing a scaffold with custom mixtures of a polymer for the former and a ceramic for the latter with imbedded pores that would allow the patient’s own cells and blood vessels to infiltrate the implant, eventually allowing it to become part of the natural bone and cartilage. The next step of the project will look to determine how to print an osteochondral implant that perfectly fits a specific patient and allows the porous implant to grow into, and function with, the bone and cartilage.
This development is one example of the lab’s main focus: improving patient health and overcoming medical challenges through innovative biomedical research. The lab houses the education and equipment needs to fabricate and characterize materials, enhancing biomaterials- related activities including developing regenerative medicine techniques, designing devices, and building prototypes. The lab is equipped with a variety of specialized equipment, including a micro-CT, numerous types of 3D printers, bioprinters, a professionalgrade electrospinning device, and other instruments, to carry out this work.
Anthony (Tony) Melchiorri, associate director of the Biomaterials Lab, gave a rundown of a typical process in the lab and how these instruments are used: A researcher can use the lab’s equipment to characterize material and then try to optimize it for the properties they are looking for with rheology and chromatography techniques. After they get the material they think is right, they 3D-print it and then use the micro-CT to make sure the material looks as it should. “It is a nice feedback loop that we have designed into the lab,” says Melchiorri.
Many factors can affect the process of developing these materials, however. Melchiorri noted that even a small factor like humidity levels can affect a researcher’s steps and results if they don’t have a controlled environment. Without a controlled environment, a material that worked well in the winter may not come out the same as in the summer, especially in a humidity- prone area like Houston, where the lab is located.
Natural versus synthetic
Melchiorri discussed how there has been a shift toward focusing on taking naturally derived materials and replacing, as much as possible, the overall reliance on synthetic materials. “We don’t have to reinvent the wheel when we can use what evolution and Mother Nature already have given us,” he said.
Even so, Melchiorri recognizes that it is still currently easier to use the lab’s biofabrication equipment with synthetic materials, because they are predictable, easy to work with, and can be controlled. “On the other hand, bioderived materials—hydrogels from gelatin or collagen—can vary batch to batch based on your source, and it can be more difficult to get uniform biologically derived materials,” he explained. Therefore, there’s been a push recently in the field of biofabrication to standardize both the materials and the techniques used to analyze the materials and figure out how researchers can translate them into 3D techniques to create actual tissues and scaffolds that have the reproducibility strength to eventually become FDA-cleared therapeutic material.
Another project currently underway at the Biomaterials Lab focuses on developing uniform and modular bioinks for hard tissues like cartilage and bone. Through a collaboration with researchers at Wake Forest University (Winston-Salem, NC), the Rice team is hoping to create a bioink that not only works on the Biomaterials Lab’s printers but that can also be replicated on various types of 3D printers, so that researchers can easily modulate the material depending on the type of tissue needed, its properties, etc.
“If we can’t reproduce our methods, there’s no way we will see it hit a patient or surgical room, so that is an evolving challenge. Naturally derived materials compound this challenge,” says Melchiorri.
Establishing collaborations and sharing their latest research developments is an important aspect of the lab. Each year, the Biomaterials Lab hosts a Biofabrication Workshop, open to all of the university’s students, staff, faculty, and researchers who are interested in biofabrication technology. The one-day event covers topics such as design considerations for 3D printing, melt-electrospinning writing, and assessing printability of custom materials. The course includes a mix of interactive lectures and discussions, as well as hands-on training of the lab’s unique instruments.
Looking toward the future, Melchiorri plans to identify and acquire additional specialized equipment needed to advance the lab’s research and hopes to expand collaborations with industry partners to ensure new innovations and solutions transfer into medical offices and hospitals.
|Brandon Martin / Rice University||Yuseon Kim|
|Yuseon Kim||Anthony Melchiorri, 2018||Jeff Fitlow / Rice University|