A First Semimanual Device for Clinical Intramuscular Repetitive Cell Injections

From Nature to Technology: Exploring the Potential of Plant-Based Materials and Modified Plants in Biomimetics, Bionics, and Green Innovations

This review explores the extensive applications of plants in areas of biomimetics and bioinspiration, highlighting their role in developing sustainable solutions across various fields such as medicine, materials science, and environmental technology. Plants not only serve essential ecological functions but also provide a rich source of inspiration for innovations in green nanotechnology, biomedicine, and architecture. In the past decade, the focus has shifted towards utilizing plant-based and vegetal waste materials in creating eco-friendly and cost-effective materials with remarkable properties. These materials are employed in making advancements in drug delivery, environmental remediation, and the production of renewable energy. Specifically, the review discusses the use of (nano)bionic plants capable of detecting explosives and environmental contaminants, underscoring their potential in improving quality of life and even in lifesaving applications. The work also refers to the architectural inspirations drawn from the plant world to develop novel design concepts that are both functional and aesthetic. It elaborates on how engineered plants and vegetal waste have been transformed into value-added materials through innovative applications, especially highlighting their roles in wastewater treatment and as electronic components. Moreover, the integration of plants in the synthesis of biocompatible materials for medical applications such as tissue engineering scaffolds and artificial muscles demonstrates their versatility and capacity to replace more traditional synthetic materials, aligning with global sustainability goals. This paper provides a comprehensive overview of the current and potential uses of living plants in technological advancements, advocating for a deeper exploration of vegetal materials to address pressing environmental and technological challenges.

Efficacy of mesenchymal stem cell-delivery using perpendicular multi-needle injections to the skin: Evaluation of post-ejection cellular health and dermal delivery

AIM

Mesenchymal stem cell (MSC)-therapy is increasingly being evaluated in clinical trials. Dermal delivery is not only time consuming but also unreliable, potentially hampering the therapeutic result. Therefore, qualification of cell delivery protocols is essential. This study evaluated a clinically relevant automated multi-needle injection method for cutaneous MSC-therapy, allowing the skin to be readily and timely treated, by assessing both the cellular health post-ejection and dermal delivery.

METHODS

Following dispensation through the injector (31 G needles: 9- or 5-pin) the cellular health and potency (perceived- and long-term (12 h) viability, recovery, metabolism, adherence, proliferation and IDO1-expression) of adipose-derived stem cells (10-20-50 ×10⁶ cells/ml) were assessed in vitro in addition to dermal delivery of solution in human skin.

RESULTS

No significant detrimental effect on the perceived cell viability, recovery, metabolism, adherence or IDO1-expression of either cell concentration was observed. However, the overall long-term viability and proliferation decreased significantly regardless of cell concentration, nonetheless marginally. An injection depth above 1.0 mm resulted in all needles piercing the skin with dermal delivery from up to 89% needles and minimal reflux to the skin surface, and the results were confirmed by ultrasound and histology.

CONCLUSION

The automated injector is capable of delivering dermal cell-doses with an acceptable cell quality.

De Novo Circulating Antidonor's Cell Antibodies During Induced Acute Rejection of Allogeneic Myofibers in Myogenic Cell Transplantation: A Study in Nonhuman Primates

Background

Transplantation of myogenic cells has potential applications in the treatment of muscle pathologies. Excluding purely autologous cell transplantation, graft viability depends on an adequate control of acute rejection (AR). To contribute in understanding AR in this context, we analyzed whether de novo circulating antibodies against donor’s cells are detected during induced AR of graft-derived myofibers in nonhuman primates.

Methods

We allotransplanted satellite cell-derived myoblasts in macaques immunosuppressed with tacrolimus. To induce AR of graft-derived myofibers, we administered tacrolimus for 4 weeks to allow complete myofiber formation, and then we stopped tacrolimus administration. Cell-grafted sites were biopsied at tacrolimus withdrawal and then every 2 weeks and analyzed by histology until AR completion. Blood samples were taken before immunosuppression, at tacrolimus withdrawal and then every 2 weeks to detect antibodies against the donor’s cells by flow cytometry.

Results

There was an increase of antibodies against the donor’s cells related to AR in all monkeys. This increase was variable in intensity, and preceded, coincided or followed the histological evidence of AR (focal accumulations of lymphocytes) and/or the loss of myofibers of donor origin, and remained until the end of the follow-up (up to 8 weeks after tacrolimus withdrawal).

Conclusions

Flow cytometry detection of de novo circulating antibodies against the donor’s cells was consistently associated with AR. A clear increase in this antibody detection indicated current or recent AR. Smaller increases in comparison to the preimmunosuppression values were not associated with AR.

Perfusion decellularization of a human limb: A novel platform for composite tissue engineering and reconstructive surgery

Muscle and fasciocutaneous flaps taken from autologous donor sites are currently the most utilized approach for trauma repair, accounting annually for 4.5 million procedures in the US alone. However, the donor tissue size is limited and the complications related to these surgical techniques lead to morbidities, often involving the donor sites. Alternatively, recent reports indicated that extracellular matrix (ECM) scaffolds boost the regenerative potential of the injured site, as shown in a small cohort of volumetric muscle loss patients. Perfusion decellularization is a bioengineering technology that allows the generation of clinical-scale ECM scaffolds with preserved complex architecture and with an intact vascular template, from a variety of donor organs and tissues. We recently reported that this technology is amenable to generate full composite tissue scaffolds from rat and non-human primate limbs. Translating this platform to human extremities could substantially benefit soft tissue and volumetric muscle loss patients providing tissue- and species-specific grafts. In this proof-of-concept study, we show the successful generation a large-scale, acellular composite tissue scaffold from a full cadaveric human upper extremity. This construct retained its morphological architecture and perfusable vascular conduits. Histological and biochemical validation confirmed the successful removal of nuclear and cellular components, and highlighted the preservation of the native extracellular matrix components. Our results indicate that perfusion decellularization can be applied to produce human composite tissue acellular scaffolds. With its preserved structure and vascular template, these biocompatible constructs, could have significant advantages over the currently implanted matrices by means of nutrient distribution, size-scalability and immunological response.

Translational considerations in injectable cell-based therapeutics for neurological applications: concepts, progress and challenges

Significant progress has been made during the past decade towards the clinical adoption of cell-based therapeutics. However, existing cell-delivery approaches have shown limited success, with numerous studies showing fewer than 5% of injected cells persisting at the site of injection within days of transplantation. Although consideration is being increasingly given to clinical trial design, little emphasis has been given to tools and protocols used to administer cells. The different behaviours of various cell types, dosing accuracy, precise delivery, and cell retention and viability post-injection are some of the obstacles facing clinical translation. For efficient injectable cell transplantation, accurate characterisation of cellular health post-injection and the development of standardised administration protocols are required. This review provides an overview of the challenges facing effective delivery of cell therapies, examines key studies that have been carried out to investigate injectable cell delivery, and outlines opportunities for translating these findings into more effective cell-therapy interventions.

Cell therapy in muscular dystrophies: many promises in mice and dogs, few facts in patients

INTRODUCTION

Muscular dystrophies (MDs) are genetic diseases that produce progressive loss of skeletal muscle fibers. Cell therapy (CT) is an experimental approach to treat MD. The first clinical trials of CT in MD conducted in the 1990s were based on myoblast transplantation (MT). Since they did not yield the expected results, several researchers sought to discover other cells with more advantageous properties than myoblasts whereas others sought to improve MT.

AREAS COVERED

We explain the properties that are required for a cell to be used in CT of MD. We briefly review most of the cells that were proposed for this CT, and to what extent these properties were met not only in laboratory animals but also in clinical trials.

EXPERT OPINION

Although the repertoire of cells proposed for CT of MD has been expanded since the 1990s, only myoblasts have currently demonstrated unequivocally to significantly engraft in humans. Indeed, MT for MD involves significant technical challenges that need be solved. While it would be ideal to find cells involving less technical challenges for CT of MD, there is so far no clinical evidence that this is possible and therefore the work to improve MT should continue.

Administration of a soluble activin type IIB receptor promotes the transplantation of human myoblasts in dystrophic mice

Duchenne muscular dystrophy (DMD) is a recessive disease caused by a dystrophin gene mutation. Myoblast transplantation permits the introduction of the dystrophin gene into dystrophic muscle fibers. However, this strategy has so far produced limited results. Modulation of transforming growth factor-β (TGF-β) superfamily signaling promotes skeletal muscle differentiation and growth and myogenic regeneration. We investigated the possibility that the combination of TGF-β superfamily signaling inhibition with myoblast transplantation might be an effective therapeutic approach in dystrophin-deficient patients. In vitro, blocking myostatin and other ligands with a soluble form of the extracellular domain of the activin IIB receptor (ActRIIB/Fc) upregulated the expression of myogenic differentiation factors and increased human myoblast fusion. In vivo, systemic inhibition of activin IIB receptor signaling by delivery of ActRIIB/Fc increased the success of the myoblast transplantation. This effect was further increased by forcing the mice to swim weekly to induce cycles of muscle degeneration and regeneration. Treatment of dystrophic mice with ActRIIB/Fc led to increased body weight, increased skeletal muscle mass, and improved myoblast transplantation. Thus, ActRIIB/Fc represents an effective therapeutic strategy for muscular dystrophies, and its effects are enhanced when combined with muscle exercise.

The skeletal muscle satellite cell: still young and fascinating at 50

The skeletal muscle satellite cell was first described and named based on its anatomic location between the myofiber plasma and basement membranes. In 1961, two independent studies by Alexander Mauro and Bernard Katz provided the first electron microscopic descriptions of satellite cells in frog and rat muscles. These cells were soon detected in other vertebrates and acquired candidacy as the source of myogenic cells needed for myofiber growth and repair throughout life. Cultures of isolated myofibers and, subsequently, transplantation of single myofibers demonstrated that satellite cells were myogenic progenitors. More recently, satellite cells were redefined as myogenic stem cells given their ability to self-renew in addition to producing differentiated progeny. Identification of distinctively expressed molecular markers, in particular Pax7, has facilitated detection of satellite cells using light microscopy. Notwithstanding the remarkable progress made since the discovery of satellite cells, researchers have looked for alternative cells with myogenic capacity that can potentially be used for whole body cell-based therapy of skeletal muscle. Yet, new studies show that inducible ablation of satellite cells in adult muscle impairs myofiber regeneration. Thus, on the 50th anniversary since its discovery, the satellite cell's indispensable role in muscle repair has been reaffirmed.

Injection Parameters Affect Cell Viability and Implant Volumes in Automated Cell Delivery for the Brain

The technique of central nervous system cell implantation can affect the outcome of preclinical or clinical studies. Our goal was to evaluate the impact of various injection parameters that may be of consequence during the delivery of solute-suspended cells. These parameters included ( 1 ) the type and concentration of cells used for implantation, ( 2 ) the rate at which cells are injected (flow rate), ( 3 ) the acceleration of the delivery device, ( 4 ) the period of time between cell loading and injection into the CNS (delay), and ( 5 ) the length and gauge of the needle used to deliver the cells. Neural progenitor cells (NPCs) and bone marrow stromal cells (BMSCs) were injected an automated device. These parameters were assessed in relation to their effect on the volume of cells injected and cell viability. Longer and thinner cannulae and higher cell concentrations were detrimental for cell delivery. Devices and techniques that optimize these parameters should be of benefit.

Angiographic Demonstration of Neoangiogenesis after Intra-arterial Infusion of Autologous Bone Marrow Mononuclear Cells in Diabetic Patients with Critical Limb Ischemia

Critical limb ischemia in diabetic patients is associated with high rates of morbidity and mortality. Suboptimal responses to the available medical and surgical treatments are common in these patients, who also demonstrate limited vascular homeostasis. Neovasculogenesis induced by stem cell therapy could be a useful approach for these patients. Neovasculogenesis and clinical improvement were compared at baseline and at 3 and 12 months after autologous bone marrow-derived mononuclear cell (BMMNC) transplantation in diabetic patients with peripheral artery disease. We conducted a prospective study to evaluate the safety and efficacy of intra-arterial administration of autologous BMMNCs (100–400 × 106 cells) in 20 diabetic patients with severe below-the-knee arterial ischemia. Although the time course of clinical effects differed among patients, after 12 months of follow-up all patients presented a notable improvement in the Rutherford-Becker classification, the University of Texas diabetic wound scales, and the Ankle-Brachial Index in the target limb. The clinical outcome was consistent with neovasculogenesis, which was assessed at 3 months by digital subtraction angiography and quantified by MetaMorph software. Unfortunately, local cell therapy in the target limb had no beneficial effect on the high mortality rate in these patients. In diabetic patients with critical limb ischemia, intra-arterial perfusion of BMMNCs is a safe procedure that generates a significant increase in the vascular network in ischemic areas and promotes remarkable clinical improvement.

Stem cell therapy for chronic heart failure: lessons from a 15-year experience

Although cell therapy has entered the clinical arena since 2000, its benefits are still controversial. This is partly due to a shift of the whole paradigm from the mere provision of new cells intended to replenish the pool of dead cardiomyocytes to the exploitation of the cell's paracrine effects to activate host-associated cytoprotective signalling pathways, particularly those involved in angiogenesis, prevention of apoptosis and possibly recruitment of endogenous cells capable to mature into functional cardiomyocytes. This review will discuss how these two basic mechanisms (direct donor cell-derived myocardial regeneration versus paracrine signalling) underlie the rational selection of cells in light of the target clinical indication, with a particular focus on chronic heart failure, and will emphasize the importance of optimizing cell delivery and survival to fully exploit the potential benefits of this novel approach to acute and chronic heart diseases.

Intramuscular cell transplantation as a potential treatment of myopathies: clinical and preclinical relevant data

INTRODUCTION

Myopathies produce deficits in skeletal muscle function and, in some cases, literally progressive loss of skeletal muscles. The transplantation of cells able to differentiate into myofibers is an experimental strategy for the potential treatment of some of these diseases.

AREAS COVERED

Among the two routes used to deliver cells to skeletal muscles, that is intramuscular and intravascular, this paper focuses on the intramuscular route due to our expertise and because it is the most used in animal experiments and the only tested so far in humans. Given the absence of recent reviews about clinical observations and the profusion based on mouse results, this review prioritizes observations made in humans and non-human primates. The review provides a vision of cell transplantation in myology centered on what can be learned from clinical trials and from preclinical studies in non-human primates and leading mouse studies.

EXPERT OPINION

Experiments on myogenic cell transplantation in mice are essential to quickly identify potential treatments, but studies showing the possibility to scale up the methods in large mammals are indispensable to determine their applicability in humans and to design clinical protocols.

NUP98-HOXA10hd-expanded hematopoietic stem cells efficiently reconstitute bone marrow of mismatched recipients and induce tolerance

Gene therapy as well as methods capable of returning cells to a pluripotent state (iPS) have enabled the correction of genetic deficiencies in syngenic adult progenitors, reducing the need for immunosuppression in cell therapy approaches. However, in diseases involving mutations that lead to the complete lack of a protein, such as Duchenne muscular dystrophy, the main immunogens leading to rejection of transplanted cells are the therapeutic proteins themselves. In these cases even iPS cells would not circumvent the need for immunosuppression, and alternative strategies must be developed. One such potential strategy seeks to induce immune tolerance using hematopoietic stem cells originated from the same donor or iPS line from which the therapeutic progenitors are derived. However, donor hematopoietic stem cells (HSCs) are available in limiting numbers and embryonic stem (ES) cell-derived HSCs engraft poorly in adults. While these limitations have been circumvented by ectopic expression of HOXB4, overexpression of this protein is associated with inefficient lymphoid reconstitution. Here we show that adult HSCs expanded with a NUP98- HOXA10hd fusion protein sustain long-term engraftment in immunologically mismatched recipients and generate normal numbers of lymphoid cells. In addition, NUP98-HOXA10hd-expanded cells induce functional immune tolerance to a subsequent transplant of myogenic progenitors immunologically matched with the transplanted HSCs.