NANOFIBER TECHNOLOGY FOR CONTROLLING STEM CELL FUNCTIONS AND TISSUE ENGINEERING - Micro and Nanotechnologies in Engineering Stem Cells and Tissues - page 35

differentiability, but the full extent of their relation to natural pluripotent stem cells is
still being assessed. 44 Although additional research is needed, iPSCs are already
useful tools for drug development and modeling of diseases, and scientists hope to
use them in transplantation medicine. Viruses are currently used to introduce the
reprogramming factors into adult cells, and this process must be carefully controlled
and tested before the technique can lead to useful treatments for humans. 45
2.4 STEM CELL-NANOFIBER INTERACTIONS IN REGENERATIVE
MEDICINE AND TISSUE ENGINEERING
Research in the area of drug delivery and tissue engineering witnessed huge progress
because of their unlimited potential to improve human health. Drug delivery and
tissue engineering are closely related fields, in which both drug delivery vehicles and
tissue-engineered scaffolds need to be biodegradable and biocompatible. Controlled
drug delivery strategies not only increase the efficacy of drugs but also maximize
patient compliance, enhancing the ability to use poorly unstable/soluble and toxic
drugs. 46 Such highly selective and effective therapeutic and diagnostic modalities
can have a dramatic impact in medicine. Electrospun nanofibrous scaffolds were
used as a carrier for both hydrophilic and hydrophobic drugs, in which the
modulation of scaffold composition, morphology, and porosity are primarily carried
out for a controlled drug release. 47 In tissue engineering approaches, it is important to
recapitulate proper function and organization of native tissues as much as possible,
which is usually done by mimicking tissue properties at nanoscale. ECM provides a
natural web of tissue-specific and organized nanofibers support and maintains the
cell microenvironment. Cells reside in a unique complex environment, and hence
scaffolds for tissue engineering approaches maintain and regulate cell behavior 48
(Fig. 2.4). The design and fabrication of these substrates will require either a surface
is naturally adhere to ECM molecules or that reproduces high-affinity binding sites
for cell-associated receptors to reproduce the natural tissue organization observed in
the pancreas, liver, and cartilage. Moreover, the utilization of electrospun nano-
fibrous scaffolds as cell delivery vehicles has been substantially increased in recent
years owing, in part, to the physical similarities between nanofibrous scaffolds and
ECM found in native tissues. 49 Such approaches might even be used to regulate and
replicate in vitro cellular environment for stem cell differentiation.
2.4.1 Skin
Chronic wounds present a worldwide growing health and economic problem because of
a steadily increasing number of patients, high morbidity and risk of amputations,
unsatisfactory results of existing therapies, and heavy socioeconomic burden. Patients
with 50% total body surface area (TBSA) full-thickness wounds have only 50% of
undamaged skin left, which could be used for split-thickness skin harvesting. Donor
sites would add to the total wound size, resulting in a wound area covering 100% of the
body. 50 These donor sites heal with some scarring and may be very painful; hence, an