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International Journal of Bioprinting dECM bioink for 3D musculoskeletal tissue reg.

Figure 3. Representative illustration of the composition and cellular interactions of the extracellular matrix (ECM). Adapted with permission from
Aamodt and Grainger. 71

4. Decellularization methods tissues, resulting in cell death and rupture. Common
physical decellularization methods include freeze-thaw
The decellularization process eliminates cellular and
nuclear remnants that may trigger an immune response cycles, mechanical force, osmosis, high hydrostatic
while preserving inherent ECM components to create pressure, nonthermal irreversible electroporation
a microenvironment suitable for cell development and (NTIRE), and supercritical fluid extraction. 95–97 Physical
function. The dECM must fulfill specific requirements decellularization is often unable to completely eliminate
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for effective migration: <50 ng DNA/mg ECM dry cellular and nuclear components following cell destruction,
weight; <200 bp DNA fragment length. 91–93 Additionally, necessitating the washing of tissue to eliminate cell
the decellularization conditions should be mild to structure and genetic material. Although mechanical
prevent excessive damage to other intrinsic components techniques have successfully decellularized certain tissues,
in the ECM. The dECM can be produced using various they are often combined with enzymatic or chemical
decellularization techniques, depending on the tissue type, methods to effectively remove genetic material residues
cell composition, thickness, density, and lipid content. from the scaffold. 95,96,98
Currently, the commonly used methods can be classified
into three categories: physical, chemical, and enzymatic Freeze-thaw cycles are usually used for the
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methods. Other procedures, like ultrasound, heating, decellularization of ligament, tendon tissue, and nerve
pressurization, and electroporation, can also be used to tissue. Rapid freezing induces the formation of cytoplasmic
achieve decellularization. In this section, we detail the crystals in cells, leading to cell membrane destruction and
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three main decellularization strategies, highlighting the lysis. 96,99 Multiple freeze-thaw cycles are necessary for
factors that influence the decellularization process, as optimal results, with precise regulation of temperature
well as the advantages and disadvantages compared to change rates to avoid damaging the ECM’s ultrastructure
other methods. due to freezing. High hydrostatic pressure can also be
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4.1. Physical methods used to decellularize tissues by directly disrupting the cell
The basic principle of physical decellularization is to membrane, but it is only effective for soft tissues, such as
mechanically destroy the cell membrane structure in the liver, cornea, lung, and blood vessels. 101,102

Volume 10 Issue 5 (2024) 73 doi: 10.36922/ijb.3418