Page 593 - Read Online

Page 2 of 15 Saxena et al. Mini-invasive Surg 2020;4:62 I http://dx.doi.org/10.20517/2574-1225.2020.68

various organs. In fact, cardiovascular diseases have been major fatal causes these days. Although recent
advances in cardiac tissue engineering (CTE) such as stem cell therapy, artificial tissues and scaffold-based
systems have emerged as powerful techniques for the treatment of coronary diseases, yet the developments
[1]
of 3D printed scaffolds for the speedy treatment of the cardiac tissues are the demand of new era . The
improper flow of blood may result in myocardial infarction (MI), i.e., heart attack, simultaneously causing
damage to heart cells. This condition usually occurs due to blockage in one or more of the coronary
arteries. The situation arises due to the accrual of fats and cholesterol in and on the artery wall known
as plaque, which restricts blood flow. Thrombosis is mostly caused by the rupture of plaque, which is
explained as the structural defect or gap in the fibrous cap. This exposes the highly thrombogenic core to
[2]
[3]
the blood . The accumulation of these fats and cholesterol is known as atherosclerosis .
Percutaneous coronary intervention (PCI) is one of the most used non-surgical procedure for the
treatment of atherosclerosis. In brief, a thin flexible tube known as a catheter is used to place a small stent
(structure) in the heart vessels to open up the blood capillaries, when narrowed by the plaque . Various
[4]
materials have been utilized as a PCI tool for the treatment of MI. Soft material based hydrogels are being
used in various forms in CTE . This complex research area is being explored by various interdisciplinary
[5-7]
approaches involving material scientists, cell biologists, chemical biologists and nanotechnologists. Among
these approaches, nanotechnology has played an extensive role in the biomedical section due to the
tunable surface and material properties exploited for PCI. The surface-to-volume ratio, surface charge, and
integration with the cells and proteins make nanomaterials highly effective in various fields of biomedical
science, including CTE. The wide biomedical applications of nanotechnology include but are not limited to
drug delivery , tissue engineering [10,11] , hyperthermia [12,13] , and nanoantibiotics [14-17] .
[8,9]
Various nanomaterials have also been utilized for the designing of PCI, and are being explored for their
practical applicability. These nanomaterials possess unique mechanical properties for their applications in
[7]
PCI for the treatment of MI. A few of the most studied materials used for PCI are alginate , chitosan ,
[18]
[19]
[20]
polyethylene glycol (PEG) and extracellular matrix (ECM) . In this review, we mostly focus on these
four materials as hydrogels for PCI applications. We discuss the structure, biochemical interactions, and
applications of these materials for PCI referring to a few of the recent studies. Additionally, we discuss the
future prospects of these materials to be utilized for CTE as well as in the treatment of the MI.
HYDROGEL-BASED CORONARY INTERVENTIONS
Hydrogels are chemically or physically cross-linked hydrophilic polymers, which possess effective
mechanical as well as the chemical properties. These hydrogels are usually capable of absorbing biological
fluids many times their weight, making them suitable for various biomedical applications. However, the
major issue with hydrogels remains their toxicity to biological system. The residual monomer, cross-linker
and catalysts cause the toxicity after the degradation of hydrogels . As discussed above, various material-
[21]
based hydrogels have been utilized for applications in PCI. PCI-based strategies may help damaged cardiac
tissues to recover; however, severe cases require the implantation of ventricular assist devices, creating
an invasive method for the treatment. The advancements in this field are ongoing with interdisciplinary
approaches for the PCI-based treatments. A few of the recent advances using alginate-, ECM- and PEG-
based hydrogels and their salient features are listed in Table 1.

The stiffness of materials, bioactivity, and biodegradability are the key factors that play an important role
in the selection of hydrogels for PCI . Nanotechnology in this regard provides an upper hand to the
[30]
researchers to tune these properties by controlling the size, structure and morphology of the materials.
However, each of these properties is crucial in the selection and rejection of the stent, yet the inherent
properties of the material control the desired reactions. For example, the cross-linking of the materials
[19]
controls the stiffness of the hydrogels . In addition, the swelling and the degradation behavior are also