Genome-edited rabbits:Unleashing the potential of a promising experimental animal model across diverse diseases

Animal models are extensively used in all aspects of biomedical research,with substantial contributions to our understanding of diseases,the development of pharmaceuticals,and the exploration of gene functions.The field of genome modification in rabbits has progressed slowly.However,recent advancements,particularly in CRISPR/Cas9-related technologies,have catalyzed the successful development of various genome-edited rabbit models to mimic diverse diseases,including cardiovascular disorders,immunodeficiencies,agingrelated ailments,neurological diseases,and ophthalmic pathologies.These models hold great promise in advancing biomedical research due to their closer physiological and biochemical resemblance to humans compared to mice.This review aims to summarize the novel gene-editing approaches currently available for rabbits and present the applications and prospects of such models in biomedicine,underscoring their impact and future potential in translational medicine.

Thermo-oxidative ageing behavior of cerium oxide/silicone rubber

Cerium oxide/silicon rubber was prepared via mechanical blending.Mechanical and frictional properties,as well as thermal stability after thermo-oxidative ageing were investigated in this rubber composite.3D surface profilometry,scanning electron microscopy(SEM)and thermogravimetry analysis(TGA)were used to study the friction surface characteristics,friction mechanism and thermal stability,respectively.Additionally,swelling experiments were carried out to investigate the variation of crosslinking density.After thermo-oxidative ageing,the tear strength of cerium oxide/silicon rubber decreases.However,in the early ageing stage,improvements in tensile strength,elongation at break,and frictional performance are caused by crosslinking density increments.Moreover,the addition of cerium oxide remarkably improves the re-cross linking degree during ageing process,which in turn decreases the number of holes on the friction surface and endows the silicon rubber with better mechanical and frictional properties,as well as thermo-oxidative ageing resistance.

Near-infrared light activated persistent luminescence nanoparticles via upconversion

Persistent luminescence nanoparticles （PLNPs） and upconversion nanoparticles （UCNPs） are two special optical imaging nanoprobes. In this study, efficient upconverted persistent luminescence （UCPL） is realized by combining their unique features into polymethyl methacrylate, forming a film composed of both PLNPs and UCNPs. The red persistent luminescence （-640 nm） of the PLNPs （CaS：Eu,Tm, Ce） can be activated by upconverted green emission of UCNPs （-NaYF4：Yb, Er@NaYF4） excited by near-infrared light （NIR）. Using this strategy, both the unique optical properties of PLNPs and UCNPs can be optimally synergized, thus generating efficient upconversion, photoluminescence, and UCPL simultaneously. The UCPL system has potential applications in in vivo bioimaging by simply monitoring the biocompatible low power density of NIR-light-excited persistent luminescence. Due to its simplicity, we anticipate that this method for the preparation of UCPL composite can be easily adjusted using other available upconversion and persistent phosphor pairs for a number of biophotonic and photonic applications.

Efficient and high-fidelity base editor with expanded PAM compatibility for cytidine dinucleotide

Cytidine base editor(CBE),which is composed of a cytidine deaminase fused to Cas9 nickase,has been widely used to induce C-to-T conversions in a wide range of organisms.However,the targeting scope of current CBEs is largely restricted to protospacer adjacent motif(PAM)sequences containing G,T,or A bases.In this study,we developed a new base editor termed“nNme2-CBE”with excellent PAM compatibility for cytidine dinucleotide,significantly expanding the genome-targeting scope of CBEs.Using nNme2-CBE,targeted editing efficiencies of 29.0%-55.0%and 17.3%—52.5%were generated in human cells and rabbit embryos,respectively.In contrast to conventional nSp-CBE,the nNme2-CBE is a natural high-fidelity base editing platform with minimal DNA off-targeting detected in vivo.Significantly increased efficiency in GC context and precision were determined by combining nNme2Cas9 with rationally engineered cytidine deaminases.In addition,the Founder rabbits with accurate single-base substitutions at Fgf5 gene loci were successfully generated by using the nNme2-CBE system.These novel nNme2-CBEs with expanded PAM compatibility and high fidelity will expand the base editing toolset for efficient gene modification and therapeutic applications.

The “bottom-up” synthesis and applications of persistent luminescence nanoparticles

Persistent luminescence refers to the phenomenon whereby luminescence remains after excitation ceases.In the past few decades,various kinds of persistent luminescent materials have been developed and widely employed in numerous applications,such as security signs,medical diagnostics and photocatalysis.Persistent luminescent materials offer distinctive advantages for biomedical applications,especially for bioimaging,as they can efficiently avoid autofluorescence and tissue-scattered light interference[1].

Low-Dose X-Ray Activated Self-luminous Bone Cement with NIR-to-NIR Pseudo-upconverted Persistent Luminescence Sensitized by Nd

X-ray activated near-infrared(NIR)persistent luminescence has promising application in biomedical luminous imaging.However,there are strict medical restrictions on X-ray dosage to avoid radiation disease.There is a need to develop a simple strategy to improve persistent luminescence imaging quality using low-dose X-ray.NIR photo-stimulation can enhance the persistent luminescence intensity by transporting the stored energy from deep traps to shallow ones,so that enhanced upconversion-like NIR-to-NIR persistent luminescence imaging can be conducted after low-dose X-ray excitation.However,existing NIR persistent luminescence phosphors have limited absorption in the NIR.To realize optimized NIR photostimulation,Nd^(3+)is proposed as a potential sensitizer to enhance the absorption of persistent luminescence phosphor to 808 nm light.In this study,ZnGa_(2)O_(4):Sn_(0.1),Cr_(0.003),Nd_(0.01)(ZGSC-Nd)was synthesized with a persistent luminescence peak at~700 nm.After activation with 1 Gy of X-ray,its persistent luminescence attenuated to less than 5%of its original intensity after 2800 s.Interestingly,the nearly vanished persistent luminescence was enhanced 5 times after 808 nm photo-stimulation,which was assigned to Nd absorption.Thus,a pseudo-upconverted persistent luminescence from 808 to 700 nm was realized more efficiently.A Nd-sensitized NIR photo-stimulated persistent luminescence mechanism was proposed.This phenomenon was applied for improved luminous imaging of ZGSC-Nd labeled bone cement after a single low-dose X-ray imaging.This work provides an applicable strategy to realize better persistent luminescence imaging after low-dose X-ray activation and will be significant on designing X-ray activated persistent phosphors for biomedical application.

Efficient multinucleotide deletions using deaminase-Cas9 fusions in human cells

CRISPR/Cas9 system is a robust genome editing platform in biotechnology and medicine.However,it generally produces small insertions/deletions(indels,typically 1-3 bp)but rarely induces larger deletions in specific target sites.Here,we report a cytidine deaminase-Cas9 fusion-induced deletion system(C-DEL)and an adenine deaminase-Cas9 fusion-induced deletion system(A-DEL)by combining Cas9 with rat APOBEC1(r A1)and Tad A 8e,respectively.Both C-DEL and A-DEL improve the efficiency of deletions compared with the conventional Cas9 system in human cells.In addition,the C-DEL system generates a considerable fraction of predictable multinucleotide deletions from 5’-deaminated C bases to the Cas9-cleavage site and increases the proportion of larger deletions at the target loci.Taken together,the CDEL and A-DEL systems provide a practical strategy for producing efficient multinucleotide deletions,expanding the CRISPR/Cas9 toolsets for gene modifications in human cells.

Targeted mutagenesis in rabbit using an engineered BhCas12b variant

Dear Editor,The clustered regularly interspaced short palindromic repeat(CRISPR)and CRISPR-associated protein(CRISPR–Cas)system has exhibited powerful abilities to manipulate genomes of animals and plants(Knott and Doudna,2018).Up to now,numerous Cas nucleases have been harnessed for genome editing in human cells,such as Cas9,Cas12a(also known as Cpf1),and Cas12b(also termed C2c1).Cas12b,a Class 2 type V-B CRISPR system,generates staggered double-strand breaks(DSBs)in the target DNA(Stella et al.,2017)and recognizes a distal 5′-T-rich protospacer adjacent motif(PAM)sequence(Shmakov et al.,2015),making it a complement to Cas9(recognizing 5′-NGG-3′PAM)in genome editing.Three Cas12b nucleases have been engineered for targeted genome editing in mammals or plants:BhCas12b v4(Strecker et al.,2019),BvCas12b(Strecker et al.,2019),and AaCas12b(Teng et al.,2018).However,they have not been compared parallelly with each other.In this study,we compared the three Cas12b proteins for genome editing in mammalian cells.