Science in a Flash – Artificial generation of tissues and organs has been a reality waiting to happen. Attempts are being made at growing different 3D organs in labs.
The advent of 3D (three-dimensional) bio-printing has opened up the prospects of printing organs and functional tissues using bio-inks. Bio-inks are a combination of polymers infused with living cells. The cells used for bio-printing are stem cells that can differentiate into any body cell.
The bio-ink based printing requires a scaffold for the construction of 3D tissues which helps in cell attachments, migration and nutrient uptake. A scaffold is a temporary platform which helps in construction of 3D structures.
However, there are several problems with the scaffold usage for building up constructs. The most common problems currently being faced in 3d science tissue engineering are un-synchronized degradation rates of scaffold and toxic by-product buildup.
A 2019 research published in Materials Horizons led by Eben Alsberg has developed scaffold free 3D bio-printing. Alsberg and his colleagues used individual cell-only bio-ink, ink that lacks biomaterial carriers like thermoplastics. Their work made use of alginate microgels that sustain a liquid-like medium to support bone marrow stem cell growth.
The nozzle of the 3D science printer would directly eject the cells into a hydrogel bead bath and produce high resolution constructs (Fig.1). The gel beads support the cells and keep them in place as they are being printed. After printing, the bead matrix was exposed to Ultra-Violet light for cross-linking the beads together.
This helped in establishing cell to cell connection for the formation of stable structures. The constructs were then easily removed from the hydrogel bead bath by gentle agitation. Alsberg and team successfully constructed an ear and a rodent-sized femur from a scaffold free, cell-only bio-ink, bio-printing technique (Fig.2).
An explosion of biomedical applications has sprouted in tissue engineering and regenerative medicine due to 3D bio-printing. Bio-printing has paved the way for generation of engineered cartilage, heart tissue and hollow blood vessels. Bio-printed tissues can be used for tissue transplantation, drug discovery and cancer research.
Tissue-mimicking constructs have not only improved testing of drug efficacy but also its screening. 3D tumor models have made it possible to study cancer pathogenesis and metastasis. Currently, the cost of bio-printing is sky high.
However, as more and more innovations like those similar to Alsberg and his team’s work emerge, the costs are projected to reduce. Overall, 3D bio-printing has made enormous contributions in the field of medicine. Regenerative medicine is one such field that greatly benefits from bio-printing.
Artificially synthesized organs can be a bridge between the organ shortage dilemma and the ever growing transplantation list. Innovations like scaffold free bio-printing can create a reality where organ regeneration and transplantation in humans is no longer science fiction.
Authors: Nimra Khurram and Muhammad Mustafa