16 research outputs found
Toward a Molecular Understanding of the Mechanism of Cryopreservation by Polyampholytes: Cell Membrane Interactions and Hydrophobicity
Cryopreservation enables long-term
preservation of cells at ultralow
temperatures. Current cryoprotective agents (CPAs) have several limitations,
making it imperative to develop CPAs with advanced properties. Previously,
we developed a novel synthetic polyampholyte-based CPA, copolymer
of 2-(dimethylamino)Âethyl methacrylate (DMAEMA) and methacrylic acidÂ(MAA)
(polyÂ(MAA-DMAEMA)), which showed excellent efficiency and biocompatibility.
Introduction of hydrophobicity increased its efficiency significantly.
Herein, we investigated the activity of other polyampholytes. We prepared
two zwitterionic polymers, polyÂ(sulfobetaine) (SPB) and polyÂ(carboxymethyl
betaine) (CMB), and compared their efficiency with polyÂ(MAA-DMAEMA).
Poly-SPB showed only intermediate property and poly-CMB showed no
cryoprotective property. These data suggested that the polymer structure
strongly influences cryoprotection, providing an impetus to elucidate
the molecular mechanism of cryopreservation. We investigated the mechanism
by studying the interaction of polymers with cell membrane, which
allowed us to identify the interactions responsible for imparting
different properties. Results unambiguously demonstrated that polyampholytes
cryopreserve cells by strongly interacting with cell membrane, with
hydrophobicity increasing the affinity for membrane interaction, which
enables it to protect the membrane from various freezing-induced damages.
Additionally, cryoprotective polymers, especially their hydrophobic
derivatives, inhibit the recrystallization of ice, thus averting cell
death. Hence, our results provide an important insight into the complex
mechanism of cryopreservation, which might facilitate the rational
design of polymeric CPAs with improved efficiency
Surface-Selective Control of Cell Orientation on Cyanobacterial Liquid Crystalline Gels
Liquid crystalline hydrogels (LCGs)
with layer structures and oriented
pores were created using sacran which is a cyanobacterial heteropolysaccharide
possessing functional sulfate, carboxylate, and amide groups in common
with glycosaminoglycan. The LCG biocompatibility with L929 mouse fibroblasts
was confirmed under the appropriate conditions. Enhanced growth and
proliferation of L929 cells without exhibiting any toxicity were confirmed.
The water contact angle and protein adsorption ability on the LCG
were well-controlled by the cross-linking degree. Additionally, fibroblasts
were finely oriented on the LCG side face where layer edges made a
striped morphology on its surface, whereas the flat top faces of the
LCG did not induce any specific cell orientation
Surface-Selective Control of Cell Orientation on Cyanobacterial Liquid Crystalline Gels
Liquid crystalline hydrogels (LCGs)
with layer structures and oriented
pores were created using sacran which is a cyanobacterial heteropolysaccharide
possessing functional sulfate, carboxylate, and amide groups in common
with glycosaminoglycan. The LCG biocompatibility with L929 mouse fibroblasts
was confirmed under the appropriate conditions. Enhanced growth and
proliferation of L929 cells without exhibiting any toxicity were confirmed.
The water contact angle and protein adsorption ability on the LCG
were well-controlled by the cross-linking degree. Additionally, fibroblasts
were finely oriented on the LCG side face where layer edges made a
striped morphology on its surface, whereas the flat top faces of the
LCG did not induce any specific cell orientation
Design of Highly Selective Zn-Coordinated Polyampholyte for Cancer Treatment and Inhibition of Tumor Metastasis
Developing anticancer agents with negligible cytotoxicity
against
normal cells while mitigating multidrug resistance and metastasis
is challenging. Previously reported cationic polymers have effectively
eradicated cancers but are clinically unsuitable due to their limited
selectivity. Herein, a series of poly(l-lysine)- and nicotinic
acid-based polymers were synthesized using varying amounts of dodecylsuccinic
anhydride. Zn-coordinating polymers concealed their cationic charge
and enhanced selectivity. These Zn-bound polymers were highly effective
against liver and colon cancer cells (HepG2 and Colon 26, respectively)
and prevented cancer cell migration. They also displayed potent anticancer
activity against drug-resistant cell lines (COR-L23/R): their cationic
structure facilitated cancer cell membrane disruption. Compared to
these polymers, doxorubicin was less selective and less efficacious
against drug-resistant cell lines and was unable to prevent cell migration.
These polymers are potential cancer treatment agents, offering a promising
solution for mitigating drug resistance and tumor metastasis and representing
a novel approach to designing cancer therapeutics
pH-Responsive Polyion Complex Vesicle with Polyphosphobetaine Shells
When
a bioactive molecule is taken into cells by endocytosis, it
is sometimes unable to escape from the lysosomes, resulting in inefficient
drug release. We prepared pH-responsive polyion complex (PIC) vesicles
that collapse under acidic conditions such as those inside a lysosome.
Furthermore, under acidic conditions, cationic polymer was released
from the PIC vesicles to break the lysosome membranes. Diblock copolymers
(P<sub>20</sub>M<sub>167</sub> and P<sub>20</sub>A<sub>190</sub>)
consisting of water-soluble zwitterionic polyÂ(2-methacryloyloxyethyl
phosphorylcholine) (PMPC) block and cationic or anionic blocks were
synthesized via reversible addition–fragmentation chain transfer
(RAFT) radical polymerization. PolyÂ(3-(methacrylamidopropyl) trimethylammonium
chloride) (PMAPTAC) and polyÂ(sodium 6-acrylamidohexanoate) (PAaH)
were used as the cationic and anionic blocks, respectively. The pendant
hexanoate groups in the PAaH block are ionized in basic water and
in phosphate buffered saline (PBS), while the hexanoate groups are
protonated in acidic water. In basic water, PIC vesicles were formed
from a charge neutralized mixture of oppositely charged diblock copolymers.
At the interface of PIC vesicle and water exists biocompatible PMPC
shells. Under acidic conditions, the PIC vesicles collapsed, because
the charge balance shifted due to protonation of the PAaH block. After
collapse of the PIC vesicles, P<sub>20</sub>A<sub>190</sub> formed
micelles composed of protonated PAaH core and PMPC shells, while P<sub>20</sub>M<sub>167</sub> was released as unimers. PIC vesicles can
encapsulate hydrophilic nonionic guest molecules into their hollow
core. Under acidic conditions, the PIC vesicles can release the guest
molecules and P<sub>20</sub>M<sub>167</sub>. The cationic P<sub>20</sub>M<sub>167</sub> can break the lysosome membrane to efficiently release
the guest molecules from the lysosomes to the cytoplasm
The permeability of PN mouse and pig embryos to COOH-PLL.
<p>The embryos were exposed to FITC-labeled COOH-PLL (5% (w/v)) for 5 min. After exposure, embryos with or without washing were examined under a laser scanning microscope. Scale bars denote 50 um.</p
The kinetics of COOH-PLL in mouse oocytes.
<p>Mouse oocytes were exposed to PB1(-) supplement with FITC-labeled COOH-PLL (5% (w/v)). Green: FITC-labeled COOH-PLL.</p
The effect of COOH-PLL concentration on the number of cells in a blastocyst.
<p>The effect of COOH-PLL concentration on the number of cells in a blastocyst.</p
The effects of COOH-PLL on survival, fertility and developmental ability of vitrified mouse oocytes after IVF.
<p>Data are shown as means ± S.E.M. Different superscripts denote a significant difference (P<0.05). Numbers of oocytes used in each group were described under the treatment group.</p
<i>In vivo</i> development of porcine embryos vitrified with P20.
<p><i>In vivo</i> development of porcine embryos vitrified with P20.</p