Glucosamine-Based Supramolecular Nanotubes for Human Mesenchymal Cell Therapy

Herein, we demonstrate an example of glucosamine-based supramolecular hydrogels that can be used for human mesenchymal cell therapy. We designed and synthesized a series of amino acid derivatives based on a strategy of capping d-glucosamine moiety at the C-terminus and fluorinated benzyl group at the N-terminus. From a systematic study on chemical structures, we discovered that the glucosamine-based supramolecular hydrogel [pentafluorobenzyl (PFB)-F-Glu] self-assembled with one-dimensional nanotubular structures at physiological pH. The self-assembly of a newly discovered PFB-F-Glu motif is attributed to the synergistic effect of π–π stacking and extensive intermolecular hydrogen bonding network in aqueous medium. Notably, PFB-F-Glu nanotubes are proven to be nontoxic to human mesenchymal stem cells (hMSCs) and have been shown to enhance hMSC proliferation while maintaining their pluripotency. Retaining of pluripotency capabilities provides potentially unlimited source of undifferentiated cells for the treatment of future cell therapies. Furthermore, hMSCs cultured on PFB-F-Glu are able to secrete paracrine factors that downregulate profibrotic gene expression in lipopolysaccharide-treated human skin fibroblasts, which demonstrates that PFB-F-Glu nanotubes have the potential to be used for wound healing applications. Overall, this article addresses the importance of chemical design to generate supramolecular biomaterials for stem cell therapy

A Toolkit for Engineering Proteins in Living Cells: Peptide with a Tryptophan-Selective Ru-TAP Complex to Regioselectively Photolabel Specific Proteins

Using a chemical approach to crosslink functionally versatile bioeffectors (such as peptides) to native proteins of interest (POI) directly inside a living cell is a useful toolbox for chemical biologists. However, this goal has not been reached due to unsatisfactory chemoselectivity, regioselectivity, and protein selectivity in protein labeling within living cells. Herein, we report the proof of concept of a cytocompatible and highly selective photolabeling strategy using a tryptophan-specific Ru-TAP complex as a photocrosslinker. Aside from the high selectivity, the photolabeling is blue light-driven by a photoinduced electron transfer (PeT) and allows the bioeffector to bear an additional UV-responsive unit. The two different photosensitivities are demonstrated by blue light-photocrosslinking a UV-sensitive peptide to POI. Our visible light photolabeling can generate photocaged proteins for subsequent activity manipulation by UV light. Cytoskeletal dynamics regulation is demonstrated in living cells via the unprecedented POI photomanipulation and proves that our methodology opens a new avenue to endogenous protein modification

The Time Window for Therapy with Peptide Nanofibers Combined with Autologous Bone Marrow Cells in Pigs after Acute Myocardial Infarction

<div><p>Background</p><p>We previously showed that injection of peptide nanofibers (NF) combined with autologous bone marrow mononuclear cells (MNC) immediately after coronary artery ligation improves cardiac performance in pigs. To evaluate the clinical feasibility, this study was performed to determine the therapeutic time window for NF/MNC therapy in acute myocardial infarction (MI).</p><p>Methods and Results</p><p>A total of 45 adult minipigs were randomly grouped into 7 groups: sham or MI plus treatment with NS (normal saline), or NF or MNC alone at 1 day (1D) post-MI, or NF/MNC at 1, 4, or 7 days post-MI (N≥6). Cardiac function was assessed by echocardiography and ventricular catheterization. Compared with the NS control, pigs treated with NF/MNC at 1 day post-MI (NF/MC-1D) had the greatest improvement in left ventricle ejection fraction (LVEF; 55.1±1.6%; P<0.01 vs. NS) 2 months after MI. In contrast, pigs treated with either NF/MNC-4D or NF/MNC-7D showed 48.9±0.8% (P<0.05 vs. NS) and 43.5±2.3% (n.s. vs. NS) improvements, respectively. The +dP/dt and -dP/dt, infarct size and interstitial collagen content were also improved in the NF/MNC-1D and -4D groups but not in the -7D group. Mechanistically, MNC quality and the states of systemic inflammation and damaged heart tissue influence the therapeutic efficiency of NF/MNC therapy, as revealed by another independent study using 16 pigs.</p><p>Conclusions</p><p>Injection of NF/MNC at 1 or 4 days, but not at 7 days post-MI, improves cardiac performance and prevents ventricular remodeling, confirming the importance of early intervention when using this therapy for acute MI.</p></div

NF/MNC injection increases transplant cell retention after MI.

<p><b>(A)</b> Representative DiI⁺ MNC (red) after injection with or without NF at 1, 4, and 7 days post-infarction. Nuclei were stained using DAPI. <b>(B)</b> The statistics of DiI⁺ MNC retention ratio. Data are presented as the mean±SEM. *<i>P</i><0.05, ***<i>P</i><0.001. Scale bar = 100 μm.</p

NF/MNC injection improves cardiac hemodynamics depending on the injection time.

<p><b>(A)</b> Hemodynamic parameters in pigs at 2 months post-MI, including pressure increment (+dP/dt), <b>(B)</b> pressure decrement (-dP/dt), <b>(C)</b> left ventricle end-diastolic pressure (LVEDP), and <b>(D)</b> volume (LVEDV), <b>(E)</b> maximum chamber elasticity (Emax), and <b>(F)</b> cardiac output (CO). Data are presented as the mean±SEM. *<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.001.</p

NF/MNC injection protects myocardial function depending on the injection time.

<p><b>(A)</b> Following surgical ligation of the mid-left anterior descending coronary artery to induce MI, the pigs underwent intramyocardial injection of NF and/or MNC at 1, 4, or 7 days and were sacrificed at 2 months after MI. Echocardiography and ventricular catheterization were used to measure cardiac function. <b>(B)</b> Showing are histograms of the left ventricle ejection fraction (LVEF, %), <b>(C)</b> the interventricular septum (IVS) systolic, and <b>(D)</b> diastolic thicknesses. Data are presented as the mean±SEM. *<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.001.</p

Early stage NF/MNC injection increases capillary density at the border zone.

<p><b>(A)</b> Representative immunostaining of isolectin (green) overlapped with troponin I (red) in the peri-infarct border zone. Nuclei were stained using DAPI (blue). <b>(B)</b> Quantification of the capillary density at the border zone. Data are presented as the mean±SEM. *<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.001. Scale bar = 100 μm.</p

NF/MNC injection at early time points post-MI decreases infarct size.

<p>(<b>A)</b> Representative images of fresh heart sections from the apex to the mid-ventricle from each group. Arrows indicate the infarcted area (scale bar = 3 cm). <b>(B)</b> Statistical analysis of infarct size and <b>(C)</b> infarct length. Data are presented as the mean±SEM. *<i>P</i><0.05, ***<i>P</i><0.001.</p

Cardiac morphology and function worsens at later time points post-infarction.

<p><b>(A)</b> Images represent cardiomyocyte disruption and inflammatory cell infiltration in the border zone by H&E staining (10X, scale bar = 100 μm). <b>(B)</b> Images represent the infarct area (left of the yellow line) and peri-infarct border zone (right of the yellow line) at 1, 4, and 7 days after myocardial infarction (MI), as well as TUNEL staining of cardiomyocytes. Green, troponin I; red, TUNEL positive cell; blue, DAPI (20X, scale bar = 100 μm). <b>(C)</b> Quantification of cardiomyocyte apoptosis following MI by TUNEL staining. <b>(D)</b> At 1, 4, and 7 days post-infarction, the left ventricle ejection fraction (LVEF, %) was measured using echocardiography and compared between different time points with N≥5 per time point. Data are presented as the mean±SEM. **<i>P</i><0.01.</p