3D Printing Human Organs

Graphical summary

Introduction

In the medical world, the global shortage of human organs is an ever-present issue. Far more people are in need of donated organs than is available, leading to prolonged wait times and therefore increasing mortality rates and reliance on less effective treatments. Additionally, there are many ethicals concerns on the fair distribution of organs because doctors must take into factors such as medical urgency and likelihood of success but also access to healthcare and socioeconomic status.

Therefore, 3D bioprinting (creating 3D structures made of biological materials, such as stem cells) is a potential solution to the shortage of human organs. Usually, materials are used to print 3D scaffolds of cells. These platforms act as a passage for cells to spread and reformulate new tissue where there is damage. This is one of many ways that 3D printing is utilized for building human organs. Because it can be highly personalized, instances where the body rejects the organ can be reduced

Bioprinting Techniques and Approaches

Fig. 1. Steps of 3D Bioprinting

1. Imaging - researchers initially take x-rays, CT scans, and MRIs to scan the body in order to determine how best to 3D print the organ

2. Design Approach

   - Biomimicry: creating exact replicas of organs

   - Autonomous self-assembly tissues: tissues that mimic embryos and their natural process of self-organization

   - Mini tissues: tissue units that are arranged to form complex structures

3. Material Selection

4. Cell Selection

5. Bioprinting

   - Inkjet printing: Regulates the size of deposited droplets with a controller

   - Extrusion bioprinting: Latest inkjet printing method, bioink is expelled through air bubbles

   - Laser-assisted printing: High-resolution deposits of ink, prints a wide variety of cells

   - Stereolithography: Utilizes UV to harden polymer layers after ink deposition

Fig. 2. Simplified illustrations of 3D bioprinting types

Each type of bioprinting has its own pros and cons. This is imperative when researching the possibilities of creating organs for possible transplants, as the body must perfectly adapt and accept the synthesized organ.

Inkjet printing

Pros - High speed, availability, low cost

Cons - Lack of precision in placement and size, need for low viscosity bioink (more fluid, easier to expel from nozzle)

Extrusion bioprinting

Pros - Can use high viscosity bioink, print high cell density (mimics conditions in the body - cells packed tightly together)

Cons - Distortion of cell structure

Laser-assisted printing

Pros - High precision, can use high viscosity

Cons - Time consuming, high costs

Stereolithography

Pros - High degree of accuracy, low printing time

Cons - Use of UV, lengthy post-processing (modifications before final product), lack of compatible materials

Clinical Applications of 3D Bioprinting

Fig. 3. Application of 3D bioprinting

There are many potential clinical applications, such as addressing the global organ shortage, being able to stop animal testing for drugs, joint repairs, tissue stimulation for drug development and discovery, testing drug toxicity, and organ transplants.

Currently, policymakers are looking to set more regulations for 3D printed organs. However, the technology is still in its stages and will take a while to create dendable, effective 3D printing methods and to perform clinical trials. A few general guidelines are set by the FDA with a few older bioprinting methods. On the bright side, this field of biotechnology is one many researchers are delving into and is expected to grow quickly.