PEPTIDE SELF-ASSEMBLY BIOMATERIALS DESIGN AND APPLICATION - Biologically-Responsive Hybrid Biomaterials - page 77

which allow tissue cells to reside and migrate in a 3D environment. Moreover,
molecules, such as growth factors and nutrients diffuse in and out of the scaffold
very slowly. These peptide scaffolds have been used for 3D cell culture,
controlled cell differentiation, tissue engineering, cancer research, and
regenerative medicine applications (Figure 4, Table 1). For example, Zhao's lab
has investigated the influence of nanofiber matrix of self-assembling peptide
RADA16 in comparison with collagen Ⅰ and Matrigel on the malignant
phenotype of human breast cancer cell MDA-MB-231 in 3D cultures, including
the morphology, survival, proliferation rate, migration potential and the effect of
these matrices on the malignancy of cancer cells in vivo. Cellular phenomena
indicated cells presented different phenotype in 3D matrices in vitro and distinct
tumorigenicity in vivo. RADA16 as an extracellular matrix could effectively
reduce the malignant phenotype of cells in vitro and in vivo.

B

Fig. 4. (A) Encapsulation of MDA-MB-231 cells in different matrices. In upper and middle panels:
Encapsulation of breast cancer MDA-MB-231 cells in different matrices of collagen Ⅰ (left row),
RADA16 (middle row) and Matrigel (right row) hydrogels using calcein-AM staining for the living
cells for three days. These results reveal that cells in collagen Ⅰ and RADA16 have an elongated
form in cell shape while in Matrigel changed to spheroid form. In bottom panel: Light microscope
images of cells encapsulated in collagen I, RADA16 and Matrigel matrices for 5 days. F-actin (red)
and nuclear (blue) fluorescence images of morphology in collagen Ⅰ (a), RADA16 (b) and Matrigel
(c). 3D cultures were stained for F-actin and nuclei were counterstained with DAPI. In collagen Ⅰ
and RADA16 3D cultures, cells with elongated cell body and projections indicate a spindle-shaped
morphology. In Matrigel, cells form colonies with disorganized nuclei which are in sharp contrast
with cells in the other two matrices. (B) Protective effects of self-assembling peptide nanofiber
(SAPNF) on islet viability and apoptosis. The viability of islets was detected by MTT assay (a).
The apoptotic rate was determined by flow cytometry (b). And Function improving effects of self-
assembling peptide nanofiber (SAPNF) on islets. The actual quantity of insulin released under
high-glucose stimulation was detected by radioimmunoassay (c) . The glucose stimulation index
was calculated as described previously (d) . Results are presented as means ± standard deviations
( n = 3). * P < .05 versus islets alone. (Images courtesy of Yangrong Lu)