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Parfenov, et al.
types of 3D bioprinting technology: (i) Ink-jet with this definition, it is easy to demonstrate
bioprinting, (ii) extrusive bioprinting, and (iii) that many so-called scaffold-free technologies
laser-based bioprinting such as laser-induced are scaffold-based. For example, (i) based on
forward transfer (LIFT) . However, in recent the most cited paper by Gabor Forgacs’s group
[4]
reviews, especially in the market reports, new on scaffold-free tissue engineering, removable
[11]
types of 3D bioprinting – magnetic and acoustic agarose hydrogel is not considered as a scaffold ;
bioprinting were also mentioned [5-8] . (ii) the removable supporting metallic needles
3D bioprinter is defined as a robotic device in the most popular and already automated and
for additive (“layer-by-layer”) biofabrication commercialized scaffold-free tissue engineering
of 3D tissue and organs in correspondence technology are not considered as temporal
[12]
with digital models. Of note, a question is still support or scaffold ; and (iii) in the so-called
under discussion – can magnetic and acoustic scaffold-free bioprinting technology that is based
bioprinters be considered as real bioprinters, or on LIFT, fibrin hydrogel is not mentioned as a
[13]
must a new term “bioassemblers” be introduced scaffold . The absence of a clear definition of
to define the new type of equipment? There are scaffold-free technology leads to some semantic
still no commercially available magnetic or confusion when authors use some sort of materials
acoustic bioprinters. It is important to note that as temporal and removable support, and claim
the development of scientific instrumentation is their techniques as “scaffold-free.” Conceptually,
essential for technological progress and advances if it is not a scaffold-free but still scaffold-based
in the new research field. Thus, the focus of this technology, then it automatically loses its
paper is a presentation of a new custom-designed desirable principal conceptual novelty. We are
magnetic levitational bioassembler as a new type facing the situation when some researchers who
of device for rapid formative biofabrication of 3D try to show pseudo-novelty and attract attention
tissue and organs. We also outline the conceptual are using certain semantic tricks. The logical
framework for a new emerging biomedical question arises: Does any actual scaffold-free
field, which we call scaffold-free, label-free, or material-free tissue engineering technology
and nozzle-free formative biofabrication. The exist? For example, magnetic force-based tissue
scaffold-free and label-free magnetic levitational engineering (Mag-TE) could also be considered
bioassembly are illustrative examples of emerging as a scaffold-free or material-free technology.
formative biofabrication. Finally, although many However, in our opinion, nanoparticles be
researchers [5-8] and market analysts still prefer to classified just as a new form of scaffold or at least
temporal and removable supporting structure with
use the more familiar term “magnetic bioprinter,” both intracellular and extracellular localization.
we hold a genuine belief that the name “magnetic Thus, Mag-TE is not material-free and cannot be
levitational bioassembler” is more relevant to considered as scaffold-free technology.
nozzle-free technology.
3 Label-based magnetic tissue engineering
2 What does the “scaffold-free” approach
mean? Mag-TE is a type of scaffold-free but label-based
biofabrication that uses magnetic nanoparticles
Rapidly emerging scaffold-free tissue engineering for enabling magnetic levitation. This technology
is a potential alternative to traditional scaffold- was initially developed by Ito and Honda as
based tissue engineering. There are several an attempt to optimize cell sheet technology,
already published conceptual reviews on which was initially developed by Prof. Okano’s
scaffold-free tissue engineering. The scaffold group in Japan . The application of magnetic
[14]
could be broadly defined as a temporal removable nanoparticles enables manipulation, handling,
(sometimes biodegradable) support [9,10] . In line and rapid assembling of cell sheets into 3D tissue

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