Downregulating PTBP1 fails to convert astrocytes into hippocampal neurons and to alleviate symptoms in Alzheimer's mouse models.

Conversion of astroglia into functional neurons has been considered as a promising therapeutic strategy for neurodegenerative diseases. Recent studies reported that downregulation of the RNA binding protein, PTBP1, converts astrocytes into neurons in situ in multiple mouse brain regions, consequently improving pathological phenotypes associated with Parkinson's disease, RGC loss, and aging. Here, we demonstrate that PTBP1 downregulation using an astrocyte specific AAV-mediated shRNA system fails to convert hippocampal astrocytes into neurons in both male and female WT, and ß-amyloid (5×FAD) and tau (PS19) Alzheimer's disease (AD) mouse models, and fails to reverse synaptic/cognitive deficits and AD-associated pathology in male mice. Similarly, PTBP1 downregulation cannot convert astrocytes into neurons in the striatum and substantia nigra in both male and female WT mice. Together, our study suggests that cell fate conversion strategy for neurodegenerative disease therapy through manipulating one single gene, such as PTBP1, warrants more rigorous scrutiny.Significance Statement:Our results do not support some of the recent extraordinary and revolutionary claims that resident astrocytes can be directly and efficiently converted into neurons. Our study is critical for the field of neural regeneration and degeneration. In addition, our study is financially important because it may prevent other researchers/organizations wasting a vast amount of time and resources on the relevant investigations.

Intracellular tracking of drug release from pH-sensitive polymeric nanoparticles via FRET for synergistic chemo-photodynamic therapy.

BACKGROUND: Synergistic therapy of tumor is a promising way in curing cancer and in order to achieve effective tumor therapy with real-time drug release monitoring, dynamic cellular imaging and antitumor activity. RESULTS: In this work, a polymeric nanoparticle with Forster resonance energy transfer (FRET) effect and chemo-photodynamic properties was fabricated as the drug vehicle. An amphiphilic polymer of cyclo(RGDfCSH) (cRGD)-poly(ethylene glycol) (PEG)-Poly(L-histidine) (PH)-poly(ε-caprolactone) (PCL)-Protoporphyrin (Por)-acting as both a photosensitizer for photodynamic therapy (PDT) and absorption of acceptor in FRET was synthesized and self-assembled into polymeric nanoparticles with epirubicin (EPI)-acting as an antitumor drug for chemotherapy and fluorescence of donor in FRET. Spherical EPI-loaded nanoparticles with the average size of 150 ± 2.4 nm was procured with negatively charged surface, pH sensitivity and high drug loading content (14.9 ± 1.5%). The cellular uptake of EPI-loaded cRGD-PEG-PH-PCL-Por was monitored in real time by the FRET effect between EPI and cRGD-PEG-PH-PCL-Por. The polymeric nanoparticles combined PDT and chemotherapy showed significant anticancer activity both in vitro (IC50 = 0.47 µg/mL) and better therapeutic efficacy than that of free EPI in vivo. CONCLUSIONS: This work provided a versatile strategy to fabricate nanoassemblies for intracellular tracking of drug release and synergistic chemo-photodynamic therapy.