We microtome embedded organs into large-scale, dimensionally stable section stacks, scan them after histological staining and reconstruct an in silico 3D histological image with a resolution of 0.9µ. After segmentation, a proprietary 3D printing process is used to generate stromal structures that can be subsequently colonized parenchymal.
3D printing is increasingly being used to produce mostly technical constructs, especially when only small quantities or customized properties are desired. It stands to reason that the use of 3D printing techniques should also be explored for the production of artificial organs to address the shortage of donor organs. Crucial to the reproduction of organs is the precise knowledge of their 3D structure down to the cellular level. In order to be able to reproduce large organs such as the heart or lungs, a dimensionally accurate, histological large-area cutting technique with subsequent semi-automated scanning of the sections was therefore developed and, in the sense of a "proof of concept", the 3D structural data of a (pig) heart, obtained in this way, was stored in a database. Subsequent 3D printing requires procedures that must necessarily differ from those used in engineering, as biocompatibility criteria impose strict constraints. Unfortunately, many biological materials cannot be easily printed because the process requires thermal, chemical or mechanical conditions that lead to denaturation. Furthermore, the time required for printing is usually high and increases even more with spatial resolution, whereas biology requires rather fast procedures. Therefore, we have developed a printing process in which the assembly of tissue structures is separated from the printing process and only the overlap of both sub-processes, but not the printing process itself, has to be biocompatible. ("Printing of Parenchyme Separating Scaffolds, PPSS").
In this case, the boundary conditions can be made somewhat more flexible:
- The biological materials do not have to be printable
- The printing process does not have to be biocompatible in every respect
This technique is based on:
- The expression of parenchyma-separating segment structures obtained from the digitized 3D organ data
- Subsequent replacement of the pressure material with stromal support material suitable for parenchymal functionalization