Stem cells for therapy

Recent Advances in Nanovaccines Using Biomimetic Immunomodulatory Materials

The development of vaccines plays a vital role in the effective control of several fatal diseases. However, effective prophylactic and therapeutic vaccines have yet to be developed for completely curing deadly diseases, such as cancer, malaria, HIV, and serious microbial infections. Thus, suitable vaccine candidates need to be designed to elicit appropriate immune responses. Nanotechnology has been found to play a unique role in the design of vaccines, providing them with enhanced specificity and potency. Nano-scaled materials, such as virus-like particles, liposomes, polymeric nanoparticles (NPs), and protein NPs, have received considerable attention over the past decade as potential carriers for the delivery of vaccine antigens and adjuvants, due to their beneficial advantages, like improved antigen stability, targeted delivery, and long-time release, for which antigens/adjuvants are either encapsulated within, or decorated on, the NP surface. Flexibility in the design of nanomedicine allows for the programming of immune responses, thereby addressing the many challenges encountered in vaccine development. Biomimetic NPs have emerged as innovative natural mimicking biosystems that can be used for a wide range of biomedical applications. In this review, we discuss the recent advances in biomimetic nanovaccines, and their use in anti-bacterial therapy, anti-HIV therapy, anti-malarial therapy, anti-melittin therapy, and anti-tumor immunity.

A 3D-printed polycaprolactone/β-tricalcium phosphate mandibular prosthesis: A pilot animal study

OBJECTIVE

In this study, we assessed the effectiveness of a tonsil-derived mesenchymal stem cell (TMSC)-transplanted polycaprolactone/beta-tricalcium phosphate prosthesis (specifically designed for easier fixing and grafting with a single scaffold) on rabbit mandible osteogenesis.

METHODS

The mandibles of 18 rabbits were exposed, and 10 × 8-mm bone defects were made. Two rabbits did not receive implants; four were reconstructed with the scaffold control (SC) (SC group); four were reconstructed with scaffolds soaked in peripheral blood (PB) (PB group); four were reconstructed with TMSC-transplanted scaffolds (TMSC group); and four were reconstructed with differentiated osteocyte-transplanted scaffolds (DOC) (DOC group). Each rabbit was sacrificed 12 weeks after surgery, and the area of new bone formation was investigated by mechanical testing, histology, and micro-computed tomography.

RESULTS

More extended and denser new bone masses were observed in the TMSC and DOC groups, although fibrosis and vascular formation levels were similar in all groups, suggesting that the dual-structured scaffold alone provides a good environment for bone attachment and regeneration. The bone volumes of representative scaffolds from the SC, PB, TMSC, and DOC groups were 43.12, 48.35, 53.10, and 57.44% of the total volumes, respectively.

CONCLUSION

The design of the scaffold resulted in effective osteogenesis, and TMSCs showed osteogenic potency, indicating that their combination could enable effective bone regeneration.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:358-366, 2020.

Generation of Retinal Progenitor Cells from Human Induced Pluripotent Stem Cell-Derived Spherical Neural Mass

Spherical neural mass (SNM) is a mass of neural precursors that have been used to generate neuronal cells with advantages of long-term passaging capability with high yield, easy storage, and thawing. In this study, we differentiated neural retinal progenitor cells (RPCs) from human induced pluripotent stem cells (hiPSC)-derived SNMs. RPCs were differentiated from SNMs with a noggin/fibroblast growth factor-basic/Dickkopf-1/Insulin-like growth factor-1/fibroblast growth factor-9 protocol for three weeks. Human RPCs expressed eye field markers (Paired box 6) and early neural retinal markers (Ceh-10 homeodomain containing homolog), but did not photoreceptor marker (Opsin 1 short-wave-sensitive). Reverse transcription polymerase chain reaction revealed that early neural retinal markers (Mammalian achaete-scute complex homolog 1, mouse atonal homolog 5, neurogenic differentiation 1) and retinal fate markers (brain-specific homeobox/POU domain transcription factor 3B and recoverin) were upregulated, while the marker of retinal pigment epithelium (microphthalmia-associated transcription factor) only showed slight upregulation. Human RPCs were transplanted into mouse (adult 8 weeks old C57BL/6) retina. Cells transplanted into the mouse retina matured and expressed markers of mature retinal cells (Opsin 1 short-wave-sensitive) and human nuclei on immunohistochemistry three months after transplantation. Development of RPCs using SNMs may offer a fast and useful method for neural retinal cell differentiation.

Cell therapy worldwide: an incipient revolution

The regenerative medicine field is large, diverse and active worldwide. A variety of different organizational and product models have been successful, and pioneering entrepreneurs have shown both what can work and, critically, what does not. Evolving regulations, novel funding mechanisms combined with new technological breakthroughs are keeping the field in a state of flux. The field struggles to cope with the lack of infrastructure and investment, it nevertheless has evolved from its roots in human stem cell therapy and tissue and organ transplants to a field composed of a variety of products from multiple cell sources with approval for use in numerous countries. Currently, tens of thousands of patients have been treated with some kind of cell therapy.

Carbon nanotube-collagen three-dimensional culture of mesenchymal stem cells promotes expression of neural phenotypes and secretion of neurotrophic factors

Microenvironments provided by three-dimensional (3-D) hydrogels mimic native tissue conditions, supplying appropriate physical cues for regulating stem cell behaviors. Here, we focused on carbon nanotubes (CNTs) dispersed within collagen hydrogels to provide 3-D microenvironmental conditions for mesenchymal stem cells (MSCs) in stimulating biological functions for neural regeneration. Small concentrations of CNTs (0.1-1wt.%) did not induce toxicity to MSCs, and even improved the proliferative potential of the cells. MSCs cultured within the CNT-collagen hydrogel expressed considerable levels of neural markers, including GAP43 and βIII tubulin proteins by immunostaining as well as GAP43 and synapse I genes by reverse transcriptase polymerase chain reaction (RT-PCR). Of note was that neurotrophic factors, particularly nerve growth factor and brain derived neurotrophic factor, were significantly promoted by the incorporation of CNTs as confirmed by RT-PCR and Western blot analysis. A model experiment involving neuritogenesis of PC12 cells influenced by those releasing neurotrophic factors from MSCs cultured within the CNT-collagen hydrogel demonstrated the significant enhancement in neurite outgrowth behaviors. Taken together, collagen hydrogel provides excellent 3-D conditions for MSC growth, and a small incorporation of CNTs within the hydrogel significantly stimulates MSC expression of neural markers and secretion of neurotrophic factors.