Encapsulation matrices for neurotrophic factor-secreting myoblast cells

Immortalized human myoblast cell lines for the delivery of therapeutic proteins using encapsulated cell technology

Despite many promising results obtained in previous preclinical studies, the clinical development of encapsulated cell technology (ECT) for the delivery of therapeutic proteins from macrocapsules is still limited, mainly due to the lack of an allogeneic cell line compatible with therapeutic application in humans. In our work, we generated an immortalized human myoblast cell line specifically tailored for macroencapsulation. In the present report, we characterized the immortalized myoblasts and described the engineering process required for the delivery of functional therapeutic proteins including a cytokine, monoclonal antibodies and a viral antigen. We observed that, when encapsulated, the novel myoblast cell line can be efficiently frozen, stored, and thawed, which limits the challenge imposed by the manufacture and supply of encapsulated cell-based therapeutic products. Our results suggest that this versatile allogeneic cell line represents the next step toward a broader development and therapeutic use of ECT.

Myoblast Therapy: From Bench to Bedside

Myoblasts are defined as stem cells containing skeletal muscle cell precursors. A decade of experimental work has revealed many properties of myoblasts, including the stability of resulting hybrid myofibers without immune suppression, the persistence of transgene expression, and the lack of tumorigenicity. Early phase clinical trials also showed that myoblast-based therapy is a promising approach for many intractable clinical conditions, including both muscle-related and non-muscle-related diseases. The potential application of myoblast therapy may be in the treatment of genetic muscle diseases, cardiomyocyte damaged heart diseases, and urinary incontinence. This review will provide an overview of myoblast biology, along with discussion of the potential application in clinical medicine. In addition, problems in current myoblast therapy and possible future improvements will be addressed.

Synthetic polycations with controlled charge density and molecular weight as building blocks for biomaterials

A series of polycations prepared by RAFT copolymerization of N-(3-aminopropyl)methacrylamide hydrochloride (APM) and N-(2-hydroxypropyl)methacrylamide, with molecular weights of 15 and 40 kDa, and APM content of 10-75 mol%, were tested as building blocks for electrostatically assembled hydrogels such as those used for cell encapsulation. Complexation and distribution of these copolymers within anionic calcium alginate gels, as well as cytotoxicity, cell attachment, and cell proliferation on surfaces grafted with the copolymers were found to depend on composition and molecular weight. Copolymers with lower cationic charge density and lower molecular weight showed less cytotoxicity and cell adhesion, and were more mobile within alginate gels. These findings aid in designing improved polyelectrolyte complexes for use as biomaterials.

Encapsulated cellular implants for recombinant protein delivery and therapeutic modulation of the immune system

Ex vivo gene therapy using retrievable encapsulated cellular implants is an effective strategy for the local and/or chronic delivery of therapeutic proteins. In particular, it is considered an innovative approach to modulate the activity of the immune system. Two recently proposed therapeutic schemes using genetically engineered encapsulated cells are discussed here: the chronic administration of monoclonal antibodies for passive immunization against neurodegenerative diseases and the local delivery of a cytokine as an adjuvant for anti-cancer vaccines.

Injection of autologous muscle stem cells (myoblasts) for the treatment of vocal fold paralysis: a pilot study

OBJECTIVE

Autologous muscle stem cell (myoblast) therapy may be an ideal treatment for vocal fold paralysis because of its technical ease (administered by injection), its potential to restore muscular defects and dynamic function, and its autologous origin. The goal of this project was to determine whether autologous myoblast injection into the thyroarytenoid (TA) muscle after recurrent laryngeal nerve (RLN) injury could attenuate TA muscle atrophy and enhance spontaneous reinnervation.

STUDY DESIGN

This was an animal experiment.

METHODS

Unilateral RLN transection and sternocleidomastoid muscle (approximately 1 g) biopsies were performed in 16 male Wistar rats. Biopsies were used to create myoblast cultures for each animal. One month later, 10(6) autologous myoblasts labeled with fluorescent cell membrane marker (PKH26) were injected into the denervated TA of each study animal, with saline injected into controls. Animals were euthanized at 2 weeks and 2 months after myoblast injection. Outcomes included myoblast survival, TA fiber diameter and volume, and reinnervation status (motor endplate to nerve contact staining).

RESULTS

All denervated TA study specimens demonstrated viable myoblasts under fluorescent microscopy, with the myoblasts demonstrating fusion with the TA myofibers at 2 months. The myoblast-treated group had greater mean TA fiber diameter than denervated TA controls at 2 months (25.1 vs. 21.1 microm; P = .04) but not at 2 weeks (25.7 microm vs. 23.5 microm; P = .06). Mean TA volumes were greater in the myoblast-treated groups at both time points. Two of the animals in the myoblast-treated group demonstrated adductor motion at 2 months, whereas none of the 2 week study animals or controls recovered adduction. Reinnervation was not significantly different between the myoblast-treated groups and the denervated controls.

CONCLUSIONS

Autologous myoblast therapy may be a future treatment for vocal fold paralysis, with current findings demonstrating myoblast survival with attenuation of TA muscle atrophy.

Development of a Delivery System for the Continuous Endogenous Release of an Anti-Idiotypic Antibody Against Ovarian Carcinoma

The treatment of several cancers with anti-idiotype antibodies has shown promising results in animals and clinical trials. A common drawback of many anti-idiotypic antibodies is their low immunogenicity. The aim of this work was to construct a new delivery form for the anti-idiotypic antibody ACA125hFc, with the goal of improving its immunogenicity as vaccine against ovarian carcinoma. Designed on bioencapsulation technologies, we generated an in vitro depot that acts as a continuous delivery system for the anti-idiotypic antibody ACA125hFc. C2C12 myoblasts were transfected with the anti-idiotypic chimeric antibody ACA125hFc, which mimics the CA125 tumor antigen and which consists of variable regions of the monoclonal murine antibody ACA125 (currently in clinical trial) and the human IgG Fc domain. Recombinant myoblasts were encapsulated in 1-cm semipermeable, polyethersulfone (PES), or polyvinylidene difluoride (PVDF) hollow fibers, which differ in their molecular weight cutoff (MWCO). Encapsulated cells were evaluated in vitro for viability and antibody secretion over a period of 3 months. PES hollow fibers with a higher MWCO showed a twofold higher secretion rate of chACA125hFc compared to PES devices with a lower MWCO. No remarkable level of ACA125hFc could be detected for PVDF devices. The expression levels of the anti-idiotypic antibody ACA125hFc from capsules with a lower MWCO could be improved substantially, in both PES as well as PVDF, by inserting an internal polyethyleneterephtalate (PET) yarn. We conclude that murine recombinant C2C12 myoblasts encapsulated in PES as well as PVDF hollow fibers containing an internal PET matrix can act as a long-term secretion system for anti-idiotypic antibodies.

Muscle precursor cell autografting in a murine model of urethral sphincter injury

OBJECTIVE

To determine whether muscle precursor cells (MPCs) harvested from limb skeletal muscle can enhance the regeneration process of the striated urethral sphincter after injury.

MATERIAL AND METHODS

Striated urethral sphincters of male mice were injured by an injection of a myotoxic substance (notexin). In the experimental group, 2 days after injury, MPCs were enzymatically harvested from striated muscles of the lower limbs and labelled with PKH 26, then immediately re-injected into the injured urethral sphincter of the same animal. In the control group, saline buffer was injected instead of MPCs. Animals were killed 7 days or 1 month after injury and the sphincters removed for histological study (the presence of PKH 26-labelled myofibres, measurement of myofibre diameter and total number of myofibres).

RESULTS

MPC autografting accelerated sphincter muscle repair, as shown by a higher myofibre diameter (P = 0.03) and number (P = 0.01) in the experimental group than in the controls at 7 days. One month after their injection MPCs were still detectable in the regenerating sphincters and participated in the formation of new myofibres.

CONCLUSION

This study provides the experimental basis for a new therapeutic approach to urethral sphincter insufficiency after surgical or obstetrical injury, based on MPC autografting.