Each day, an average of 79 people receive organ transplants. In contrast, sadly, an average of 22 people lose their lives each day awaiting an organ, eye, or tissue transplant that wasn’t available. Every 10 minutes, someone is added to the national transplant list: what would that medical journey look like for your loved one if the organ they needed was in high demand?
In the U.S., seven types of organ transplants are performed. Kidneys are in high demand and frequently donated. The most common transplants are livers. They have a decades-long track record of success and make the perfect template for organ engineering. Over 2,600 people are waiting for a heart transplant across the U.S. Pancreas functionality is known not to be affected by making a living donation of a portion of the pancreas. The least common single-organ transplants are the intestines.
Transplant surgery is one thing, the wait on an organ transplant waiting list is quite another.
So why not sidestep this often heartbreaking process and custom cultivate a heart or liver for transplant? The vanguards behind printing functional organs are researching their way to a not-so-distant answer with the help of embryonic stem cells (ESCs) and extrusion-based 3D printers.
Earlier in 2015, Ray Kurzweil, Google’s Director of Engineering proclaimed “By 2025, 3D printers will print human organs using modified stem cells with the patient’s own DNA providing an inexhaustible supply of organs and no rejection issues. [We will] be able to reprogram human biology away from many diseases and aging processes, for example deactivating cancer stem cells that are the true source of cancer and repair damaged organs with reprogrammed stem cells.”
VANGUARDS OF ORGAN PRINTING
Scientists are launching into a reimagined reality of 3D-printed medicine. Bioficial heartbeats and prosthetic footsteps are milestones easing the regenerative future of healthcare further and further ahead. And while bioprinted organs could diminish the agonizing organ transplant wait, putting ESCs to work regenerating lost tissue after injury or disease is a game changer in itself.
These unique cells can transform into one of the 200 different types of cells in our human bodies, so it’s essential to address the current scruples regarding their sourcing. And 3D-printed ESCs would have the remarkable power to eradicate the moral dilemma and advance the exploration into custom-designed, lab-grown replacement organs, eyes, and tissues.
Beijing, China’s Tsinghua University and Philadelphia’s Drexel University researchers have teamed up to build three-dimensional grids of ESCs embedded in hydrogel. They are the first known team to successfully print blocks of ESCs in a way that would allow for cells to divide and maintain the capacity for differentiation.
In their research, the grids displayed cell viability and resilience, as well as the ability to change into various cells, or pluripotency, for up to seven days. Pluripotency is the key to growing one of four types of tissue, and, if fine-tuned, could lead research towards 3D printing groups of cells with the potential to grow into functional organs. “We are not directly going to print an organ, but we can print an in vitro 3D biological model which could lead to growing different size embryoid bodies, different types of cells, and, ultimately, to growing a regenerated organ,” said Drexel University Professor and researcher Wei Sun. “This will be a significant advance for stem cell research and for regenerative medicine.”
BIOPRINTING EMBRYONIC STEM CELLS
Previously, researchers have only been met with limitations while bioprinting ESCs in a two-dimensional format. While ESCs are especially capable of differentiating into any of an animal body’s specialized cell type, this typically only occurs through the formation of embryoid bodies (EBs), or 3-dimensional groups of ESCs, resembling the formation and development of an embryo, or embryogenesis.
Reinforcing this process would pave the way towards developing tissue that independently divides and organizes itself into complex living tissue. Or as Sun put it, “I think that we’ve produced a 3D microenvironment which is much more like that found in vivo for growing embryoid body, which explains the higher levels of cell proliferation.”
With 3D bioprinting, mimicking the beginning of embryo formation is much easier. A ball-shaped EB becomes more applicable than flat petri dishes for this particular study, so the 3D arrangement of ESC “building blocks” create an opportunity for uniformity and high precision.
“The grown embryoid body is uniform and homogenous, and serves as a much better starting point for further tissue growth [compared to 2D methods],” Sun clarified.
With the control of manipulating cells into tissue-like designs comes the means to better explore and mimic our complex cellular makeup. Doctors already know how to harvest a 3D scaffold for any of these organs in demand. Excavated material from the organ leaves scientists with the “scaffold” where the cells lived. From there, reintroduction of cells is the next step and stem cells could play a huge part. Cultivation of EBs means more flexible “lego bricks” for creating new tissue constructs, large structures of tissues, and, eventually, micro-organs.
The immortality of stem cells paired with the greater developmental potential of embryonic stem cells (versus that of adult stem cells) are great tools for uncovering the mysteries of birth defects and cancers. The future of ESCs will most likely always remain laden with controversy, but the path to controlled heterogeneous EBs and the consequential growth of micro-organs could lead to animal-friendly laboratory testing methods.
“This would promote different cell types developing next to each other—which would lead the way for growing micro-organs from scratch within the lab,” explained Researcher Rui Yao.
Would replacing lab animals with experimenting on micro-organs eradicate the moral dilemma of ESCs? Advances in bioprinting point to micro-organs as the better candidate for the job, but establishing a consistent source without a longer ethical conversation still seems like a distant dream.
As the stigma of sourcing stem cells fades into our history, researchers grow more comfortable with replicating the essential puzzle pieces of what can revive and restore us. Time will only tell what other structures can be grown from these 3D-printed building blocks, but the marvelous direction we are honing in on leaves far less loved ones on any list where they can be left waiting for a vital lifeline.
Information sourced from: 3DPrint.com, Web MD, How Stuff Works, IOP Science, The Triangle, Science Alert, io9/Gizmodo, Engineering.com, 3Ders.