Click to read abstract,Retinal degenerative diseases are one of the leading causes of permanent incurable vision loss and are often characterised by the loss of light-sensing photoreceptors. In vitro differentiation of induced pluripotent stem cells (iPSCs) into photoreceptors is a promising avenue to generate transplantable photoreceptors for vision restoration. Herein, we report an optimised protocol with significant improvements over current research in producing retinal progenitor cells of higher yield and quality. We have shortlisted three factors - seeding density, picking method (needle/pipette picked) together with clump size, and timing of rosette picking which can potentially improve the differentiation process, and this study focuses on their first-time application to retinal cells. We found that higher seeding densities (2M v. 750K) on Day 7 resulted in significantly faster rosette formation – 25% faster than currently reported. Needle-picked rosettes seeded in clumps had more uniformly shaped cells and were more homogenous than those which were pipette picked. Picking rosettes later in the differentiation protocol (Day 18 v. Day 20) reduced the cell detachment rate. Immunostaining, qRT-PCR and brightfield microscopy were employed throughout this study to quantify the quality of cells. The results contribute valuable insights for advancing iPSC-based retinal cell replacement therapies, offering hope for improved treatment outcomes for retinal degenerative disease patients.

Click to read abstract,Transition metal complexes are widely used in the industry as catalysts and dyes. To accurately predict properties of these complexes, the low-lying energy states can be calculated. Directly solving the integralsnecessary for the calculations of the low-lying energy states for transition metal complexes is extremely computationally intensive. Hence, we aim to provide a simple ligand field model of two Re(III) molecules, [ReCl6]3- and ReCl3(tppz) to accurately predict its low-lying energy states. Ab initio calculations were done with CASSCF and CASPT2. Two different model Hamiltonians were constructed with five different ligand field parameters: energy gap (J), spin-orbit coupling (?), axial (?), and rhombic distortion (e), and the orbital reduction factor (?). A nine-by-nine matrix for the 3T1 configuration, and a fifteen-by-fifteen matrix for the t2g4 configuration were obtained. The eigenvalues of the Hamiltonian were then fitted to thecalculated energy states using a minimization function. The values for the 3T1 model fit extremely well, with a mean percentage error between 10-6 % to 0.4%, whereas the t2g4 model has mean percentage errors between 0.17% and 1.3%. We obtained values for the parameters that match our predictions. For example, the value of ? and e are close to 0 for [ReCl6]3-, representing a perfect octahedral compound, and are large in magnitude for ReCl3(tppz), which is not a perfect octahedral and will have some axial and rhombic splitting. We can expand our research into fitting the five parameters to other 5d4 transition metal complexes and including more states in the Hamiltonian.