B cells exert multiple effector functions, and dysfunctions of B cells often lead to initiation and progression of diseases, including autoimmune and inflammatory diseases. Therefore, B cell intervention may be an effective strategy to treat diseases involving B cells. The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 gene editing system has been widely used for DNA deletion, insertion, and replacement. Nanocarriers have been developed as relatively mature systems and may be applied to deliver the CRISPR-Cas9 system to B cells in vivo. In this study, we created a library of nanoparticles (NPs) with different polyethylene glycol densities and zeta potentials and screened an optimal NP for in vivo B cell targeting. The selected NP could deliver the CRISPR-Cas9 system to B cells and induce Cas9 expression inside the cell environment. Injection of the NP encapsulated with Cas9/gB220 (NP_Cas9/gB220) into mice could disrupt B220 expression in B cells, suggestive of its applications to intervene the expression of the target molecule in B cells. Moreover, the treatment with NP_Cas9/gBAFFR could decrease the number of B cells and exert therapeutic effect in rheumatoid arthritis, as B-cell activating factor receptor (BAFFR) is vital for the survival and functions of B cells. In conclusion, we developed a carrier for the delivery of the CRISPR-Cas9 gene editing system for B cell intervention that could be used for the treatment of diseases related to B cell dysfunctions.

Convincing evidence indicates that the existence of cancer stem cells (CSCs) within malignant tumors is mostly responsible for the failure of chemotherapy. Therefore, instead of merely targeting bulk cancer cells, simultaneous elimination of both CSCs and bulk cancer cells is necessary to improve therapeutic outcomes. Herein, we designed cationic-lipid-assisted nanoparticles ^DTXLNP_siRNA for simultaneous encapsulation of the conventional chemotherapeutic agentdocetaxel (DTXL) and small interfering RNA (siRNA) targeting BMI-1 (siBMI-1). We confirmed that nanoparticles ^DTXLNP_siBMI-1 effectively deliver both therapeutic agents into CSCs and bulk cancer cells. The bulk cancer cells were effectively killed by the DTXL encapsulated in ^DTXLNP_siBMI-1. In breast CSCs, BMI-1 expression was significantly downregulated by ^DTXLNP_siBMI-1; consequently, the stemness was reduced and chemosensitivity of CSCs to DTXL was enhanced, resulting in the elimination of CSCs. Therefore, via ^DTXLNP_siBMI-1, the combination of siBMI-1 and DTXL completely inhibited tumor growth and prevented a relapse by synergistic killing of CSCs and bulk cancer cells in a murine model of an MDA-MB-231 orthotropic tumor.