Small steps, big impact – 3D bioprinting kidneys at Harvard
Though it takes just an instant for research to become a discovery, an apple falling from a tree; a bolt of lighting; the snap of a shutter, fully developed breakthroughs in science and medicine take years to perfect, and what we read today, about Harvard material scientists’ developments in the bioprinting of a kidney structure, is one small step closer to a future where organ transplant lists are a thing of the past.
The structure of proximal tubules found inside a human kidney Image via: Wyss Institute at Harvard University
A proximal tube (PT) is a smaller segment of a nephron – which make up the structure of a kidney in their millions. Nephrons are what enables a kidney to filter and absorb nutrients from the blood.
How is it done?
Step 1: A PT structure is printed onto a glass slide (and it looks a lot like London’s River Thames)
Step 2: Then an extracellular matrix, matter that surrounds cells within the body, is injected on top of the river-like shape
Step 3: After this, the printed ‘river’ is removed to leave a hollow mold
Step 4: Living cells are injected into the mold which acts as a guideline for the structure of a proximal tube
Step 5: As the cells grow – or culture – they take on the characteristics of native PTs and can be tested with substances such as new medicines.
3D convoluted renal proximal tubule on chip. Image via Nature’s Scientific Reports journal
The process follows the same ‘sorting-out’ concept of cell manipulation that has been used in bio-printing a miniature heartand kidneys. The process of sorting-out means that cells given a particular form eventually retain the order of the synthetic structure around them, and operate as they would in this structure within the body.
Jennifer Lewis is the lead researcher on the project. As a professor at Harvard University, and core faculty member at the Wyss Institute for Biologically Inspired Engineering, Lewis is one of the leading names in 3D bio-printing research, and has over 120 journal articles attributed to her name. Her team at Harvard also succeeded in printing thick tissues containing blood vessels earlier this year, this research served as a basis for this most recent advance.
The team’s next step is to arrange the PTs into a vascular structure, gradually building up tissue until it is suitable to be transplanted. As the researchers write in the paper,
Three-dimensional models of kidney tissue that recapitulate human responses are needed for drug screening, disease modeling, and, ultimately, kidney organ engineering. Our bioprinting method provides a new route for programmably fabricating advanced human kidney tissue models on demand.
3D printing or Additive manufacturing is a process of making a three-dimensional solid object of virtually any shape from a digital model. 3D printing is achieved using an additive process, where successive layers of material are laid down in different shapes. 3D printing is also considered distinct from traditional machining techniques, which mostly rely on the removal of material by methods such as cutting or drilling (subtractive processes).
A 3D printer is a limited type of industrial robot that is capable of carrying out an additive process under computer control.
While 3D printing technology has been around since the 1980s, it was not until the early 2010s that the printers became widely available commercially. The first working 3D printer was created in 1984 by Chuck Hull of 3D Systems Corp. Since the start of the 21st century there has been a large growth in the sales of these machines, and their price has dropped substantially. According to Wohlers Associates, a consultancy, the market for 3D printers and services was worth $2.2 billion worldwide in 2012, up 29% from 2011.[
The 3D printing technology is used for both prototyping and distributed manufacturing with applications in architecture, construction (AEC), industrial design, automotive, aerospace, military, engineering, civil engineering, dental and medical industries, biotech (human tissue replacement), fashion, footwear, jewelry, eyewear, education, geographic information systems, food, and many other fields. One study has found that open source 3D printing could become a mass market item because domestic 3D printers can offset their capital costs by enabling consumers to avoid costs associated with purchasing common household objects.
3D Printable Models
3D printable models may be created with a computer aided design package or via 3D scanner. The manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting. 3D scanning is a process of analyzing and collecting data of real object; its shape and appearance and builds digital, three dimensional models.