In Situ Synthesis of an Anticancer Peptide Amphiphile Using Tyrosine Kinase Overexpressed in Cancer Cells

Microplate-Based Cryopreservation of Adherent-Cultured Human Cell Lines Using Amino Acids and Proteins

With the progression of regenerative medicine and cell therapy, the importance of cryopreservation techniques for cultured cells continues to rise. Traditional cryoprotectants, such as dimethyl sulfoxide and glycerol, are effective in cryopreserving suspended cells, but they do not demonstrate sufficient efficacy for two-dimensional (2D)-cultured cells. In the past decade, small molecules and polymers have been studied as cryoprotectants. Some L-amino acids have been reported to be natural and biocompatible cryoprotectants. However, the cryoprotective effects of D-amino acids have not been investigated for such organized cells. In the present study, the cryoprotective effects of D- and L-amino acids and previously reported cryoprotectants were assessed using HepG2 cells cultured on a microplate without suspending the cells. d-Proline had the highest cryoprotective effect on 2D-cultured cells. The composition of the cell-freezing solution and freezing conditions were then optimized. The d-proline-containing cell-freezing solution also effectively worked for other cell lines. To minimize the amount of animal-derived components, fetal bovine serum in the cell freezing solution was substituted with bovine serum albumin and StemFit (a commercial supplement for stem cell induction). Further investigations on the mechanism of cryopreservation suggested that d-proline protected enzymes essential for cell survival from freeze-induced damage. In conclusion, an effective and xeno-free cell-freezing solution was produced using d-proline combined with dimethyl sulfoxide and StemFit for 2D-cultured cells.

Synthesizing biomaterials in living organisms

Living organisms fabricate biomacromolecules such as DNA, RNA, and proteins by the self-assembly process. The research on the mechanism of biomacromolecule formation also inspires the exploration of in vivo synthesized biomaterials. By elaborate design, artificial building blocks or precursors can self-assemble or polymerize into functional biomaterials within living organisms. In recent decades, these so-called in vivo synthesized biomaterials have achieved extensive applications in cell-fate manipulation, disease theranostics, bioanalysis, cellular surface engineering, and tissue regeneration. In this review, we classify strategies for in vivo synthesis into non-covalent, covalent, and genetic types. The development of these approaches is based on the chemical principles of supramolecular chemistry and synthetic chemistry, biological cues such as enzymes and microenvironments, and the means of synthetic biology. By summarizing the design principles in detail, some insights into the challenges and opportunities in this field are provided to  enlighten further research.

Enzyme-Instructed Intracellular Peptide Assemblies

Higher-order or supramolecular protein assemblies, usually regulated by enzymatic reactions, are ubiquitous and essential for cellular functions. This evolutionary fact has provided a rigorous scientific foundation, as well as an inspiring blueprint, for exploring supramolecular assemblies of man-made molecules that are responsive to biological cues as a novel class of therapeutics for biomedicine. Among the emerging man-made supramolecular structures, peptide assemblies, formed by enzyme reactions or other stimuli, have received most of the research attention and advanced most rapidly.In this Account, we will review works that apply enzyme-instructed self-assembly (EISA) to generate intracellular peptide assemblies for developing a new kind of biomedicine, especially in the field of novel cancer nanomedicines and modulating cell morphogenesis. As a versatile and cell-compatible approach, EISA can generate nondiffusive peptide assemblies locally; thus, it provides a unique approach to target subcellular organelles with exceptional cell selectivity. We have arranged this Account in the following way: after introducing the concept, simplicity, and uniqueness of EISA, we discuss the EISA-formed intracellular peptide assemblies, including artificial filaments, in the cell cytosol. Then, we describe the representative examples targeting subcellular organelles, such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and the nucleus, by enzyme-instructed intracellular peptide assemblies for potential cancer therapeutics. After that, we highlight the recent exploration of the transcytosis of peptide assemblies for controlling cell morphogenesis. Finally, we provide a brief outlook of enzyme-instructed intracellular peptide assemblies. This Account aims to illustrate the promise of EISA-generated intracellular peptide assemblies in understanding diseases, controlling cell behaviors, and developing new therapeutics from a class of less explored molecular entities, which are substrates of enzymes and become building blocks of self-assembly after the enzymatic reactions.

Role of Anti-Cancer Peptides as Immunomodulatory Agents: Potential and Design Strategy

The usage of peptide-based drugs to combat cancer is gaining significance in the pharmaceutical industry. The collateral damage caused to normal cells due to the use of chemotherapy, radiotherapy, etc. has given an impetus to the search for alternative methods of cancer treatment. For a long time, antimicrobial peptides (AMPs) have been shown to display anticancer activity. However, the immunomodulatory activity of anti-cancer peptides has not been researched very extensively. The interconnection of cancer and immune responses is well-known. Hence, a search and design of molecules that can show anti-cancer and immunomodulatory activity can be lead molecules in this field. A large number of anti-cancer peptides show good immunomodulatory activity by inhibiting the pro-inflammatory responses that assist cancer progression. Here, we thoroughly review both the naturally occurring and synthetic anti-cancer peptides that are reported to possess both anti-cancer and immunomodulatory activity. We also assess the structural and biophysical parameters that can be utilized to improve the activity. Both activities are mostly reported by different groups, however, we discuss them together to highlight their interconnection, which can be used in the future to design peptide drugs in the field of cancer therapeutics.