3D Printing a Human Being

Basic Principles of 3D Printing Technology

  • 3D printing is also known as Additive Manufacturing.
  • It builds up a 3D object one layer at a time.
  • The first 3D printers were invented in the 1980s.
  • all3dp.com is an excellent resource to learn about 3D printing.
  • 3D Printing is a very old concept in engineering.

Methods to Create 3D Computer Models

  • CAD.
  • Surface Scan.
  • Medical Imaging.

Why the Increasing Interest in 3D Printing?

  • The cost of this technology has rapidly decreased over the last 10 years.
  • Thousands of different 3D printers are available.
  • Starting at less than £99.

3D Printer Types

  • Material Extrusion – Fused Deposition Modeling (FDM) / Fused Filament Fabrication (FFF).
    • Solid-Liquid-Solid.
  • VAT Polymerisation – SLA / DLP.
    • Liquid-Solid.
  • Powder Bed Fusion – SLS.
    • Solid-Liquid-Solid.

3D Printer Specifications

  • Materials:
    • Hard – PLA, ABS, nylon, acrylic, metals, concrete.
    • Soft – TPU, silicone, clay.
    • Organic – chocolate, icing, cellular.
    • >50 different materials types available.
  • Layer thickness – 100100 microns.
  • In-plane resolution – 100100 microns.
  • Speed – 10 mins to days depending on object size.

3D Printing Pipeline

  • SOURCE DATA: CAD, Surface Scan, Medical Imaging.
  • 3D FILE: Segmentation.
  • SLICER: GCODE FILE.
  • 3D PRINTER: 3D PRINT.

3D Printing at King’s Health Partners

  • There are dedicated 3D printing facilities within KHP to support:
    • Clinical applications – numerous routine services.
    • Research – medical devices, anthropomorphic phantoms, implants.
    • Education – dedicated modules that teach additive manufacturing to engineering and healthcare students (year 2 Synthetic Anatomy).
  • The Medical Physics Department has a dedicated 3D Printing Centre that handles production of 3D printed models as a clinical service and for research.

Clinical Services

  • Production of cardiac models for surgical planning in patients with congenital heart disease (CHD).
    • Valverde et al. 2017, Eu. J. Cardiothorac. Surg.
    • 10 international centres, 40 patients with complex CHD.
    • 19/40 – models helped to refine surgical approach.
    • 21/40 – models did not alter the surgical approach.
  • 3D Printer: Stratasys Objet500 – material jetting multi-material.

Research – Anthropomorphic Phantoms

  • These can be used for:
    • Testing of novel medical devices.
    • Generation of synthetic medical images for training of AI algorithms.
    • Surgical procedure simulation for training & rehearsal.
    • Validation of biophysical modelling algorithms.
    • Reduce the need for patient data.
    • Reduce the need for animal experiments.
    • Reduce the need for cadaver experiments.
    • Reduce costs.

Anthropomorphic Phantoms – Cardiac Phantoms

  • Whole-heart models using soft materials
    • Lay-fomm 40, Tango Plus
    • Flsun Delta FDM, Stratasys Objet500
    • Material: Printer: Cost:
      • £30, £750
    • Shu Wang et al. 2020, J. 3DP&AM

Anthropomorphic Phantoms – Valve Phantoms

  • Valve models using 2-part moulds & silicone

Anthropomorphic Phantoms – Direct Silicone Printing

  • Direct silicone printing of valve models
    • Moulded Valve - Ecoflex 0030
    • Directly Printed Valve - Dragonskin 20
    • Custom Silicone Printer: based on Prusa i3 clone and open-source design
      • LOW COST
      • LARGE BUILD VOLUME
      • REDUCED MANUFACTURING TIME

Implants – Bone Replacement

  • For lung cancer surgery – patients with bone involvement
    • CT → 3D Model, Low-cost PLA Print, Low-cost Silicone Mould → Custom PMMA Implant
    • 15+ Patients implanted so far, No complications, Better respiratory mechanics & improved aesthetics
    • LOW COST vs TITANIUM IMPLANTS
    • Pontiki et al. 2021, ATS https://www.bbc.co.uk/iplayer/episode/m001j6cw/click-3dprinted-bones

What is 3D Bioprinting and Why do we need this?

  • 3D Bioprinting involves the use of living components to print tissues and organs
    1. Print 3D Scaffold, Seed with Cells
    2. Bioink, Print Cells Only, Print Cells + Scaffold (usually a hydrogel)
  • Could be useful for research, testing of drugs/devices and implants
    • organdonor.gov Shinkar & Rhode, Annals of 3D Printed Medicine, 2022

3D Printing with Bioinks

  • Pre-processing: Imaging (X-ray, MRI, CT, Ultrasound), Harvesting Patient's cells, Cell culture
  • Processing: Cell-laden bioink preparation, 3D Modelling & Slicing (CT Image → 3D Model STL File)
  • 3D Bioprinter
  • Post-processing: Bioreactor for tissue maturation → Matured tissue / organ
  • Application: In vitro models for disease modelling, drug/cosmetic testing, Transplanted into patients
  • Vijayavenkataramana et al, Advanced Drug Delivery Reviews 2018

Examples of 3D Bioprinting - Skin

  • Bioink with Fibroblasts + Keratinocytes, 3D Bioprinted skin
  • Pourchet et al, Advanced Healthcare Materials 2016

Examples of 3D Bioprinting – Heart Muscle

  • Bioink with Myocytes, Functional Patch of Myocardium
  • Gaetani et al, Biomaterials 2015
  • Many other structures have been bioprinted – liver, heart valves, blood vessels, trachea

Summary

  • The development of 3D printing technologies will have a huge impact on healthcare
  • Already used for medical devices, surgical planning, implants and research
  • Bioprinting is a booming research area
  • Printing of tissues & organs is challenging but progress is rapid
  • We need to consider ethical issues
  • Thank you & Questions?