Industrial Development of Standardized Fetal Progenitor Cell Therapy for Tendon Regenerative Medicine: Preliminary Safety in Xenogeneic Transplantation

Bio-Enhanced Neoligaments Graft Bearing FE002 Primary Progenitor Tenocytes: Allogeneic Tissue Engineering & Surgical Proofs-of-Concept for Hand Ligament Regenerative Medicine

Hand tendon/ligament structural ruptures (tears, lacerations) often require surgical reconstruction and grafting, for the restauration of finger mechanical functions. Clinical-grade human primary progenitor tenocytes (FE002 cryopreserved progenitor cell source) have been previously proposed for diversified therapeutic uses within allogeneic tissue engineering and regenerative medicine applications. The aim of this study was to establish bioengineering and surgical proofs-of-concept for an artificial graft (Neoligaments Infinity-Lock 3 device) bearing cultured and viable FE002 primary progenitor tenocytes. Technical optimization and in vitro validation work showed that the combined preparations could be rapidly obtained (dynamic cell seeding of 10⁵ cells/cm of scaffold, 7 days of co-culture). The studied standardized transplants presented homogeneous cellular colonization in vitro (cellular alignment/coating along the scaffold fibers) and other critical functional attributes (tendon extracellular matrix component such as collagen I and aggrecan synthesis/deposition along the scaffold fibers). Notably, major safety- and functionality-related parameters/attributes of the FE002 cells/finished combination products were compiled and set forth (telomerase activity, adhesion and biological coating potentials). A two-part human cadaveric study enabled to establish clinical protocols for hand ligament cell-assisted surgery (ligamento-suspension plasty after trapeziectomy, thumb metacarpo-phalangeal ulnar collateral ligamentoplasty). Importantly, the aggregated experimental results clearly confirmed that functional and clinically usable allogeneic cell-scaffold combination products could be rapidly and robustly prepared for bio-enhanced hand ligament reconstruction. Major advantages of the considered bioengineered graft were discussed in light of existing clinical protocols based on autologous tenocyte transplantation. Overall, this study established proofs-of-concept for the translational development of a functional tissue engineering protocol in allogeneic musculoskeletal regenerative medicine, in view of a pilot clinical trial.

Process Optimization and Efficacy Assessment of Standardized PRP for Tendinopathies in Sports Medicine: Retrospective Study of Clinical Files and GMP Manufacturing Records in a Swiss University Hospital

Platelet-rich plasma (PRP) preparations have recently become widely available in sports medicine, facilitating their use in regenerative therapy for ligament and tendon affections. Quality-oriented regulatory constraints for PRP manufacturing and available clinical experiences have underlined the critical importance of process-based standardization, a pre-requisite for sound and homogeneous clinical efficacy evaluation. This retrospective study (2013–2020) considered the standardized GMP manufacturing and sports medicine-related clinical use of autologous PRP for tendinopathies at the Lausanne University Hospital (Lausanne, Switzerland). This study included 48 patients (18–86 years of age, with a mean age of 43.4 years, and various physical activity levels), and the related PRP manufacturing records indicated a platelet concentration factor most frequently in the range of 2.0–2.5. The clinical follow-up showed that 61% of the patients reported favorable efficacy outcomes (full return to activity, with pain disappearance) following a single ultrasound-guided autologous PRP injection, whereas 36% of the patients required two PRP injections. No significant relationship was found between platelet concentration factor values in PRP preparations and clinical efficacy endpoints of the intervention. The results were in line with published reports on tendinopathy management in sports medicine, wherein the efficacy of low-concentration orthobiologic interventions appears to be unrelated to sport activity levels or to patient age and gender. Overall, this study confirmed the effectiveness of standardized autologous PRP preparations for tendinopathies in sports medicine. The results were discussed in light of the critical importance of protocol standardization for both PRP manufacturing and clinical administration to reduce biological material variability (platelet concentrations) and to enhance the robustness of clinical interventions (comparability of efficacy/patient improvement).

Current Status of PRP Manufacturing Requirements & European Regulatory Frameworks: Practical Tools for the Appropriate Implementation of PRP Therapies in Musculoskeletal Regenerative Medicine

Providing accurate and up-to-date practical tools enabling oversight of platelet-rich plasma (PRP) legislation and of the appropriate standards to be implemented for its manufacture and use in Europe is a demanding task. This is due to rapid medico-technological advancements, slowness and disparity in legislation updates and enforcement between member states, and many reported gray-zone practices, notably for autologous PRP use. The levels of risk associated with blood manipulation processes generally dictate the manufacturing requirements for PRP preparations, which have gradually shifted toward good manufacturing practices (GMP) for standardization and overall quality enhancement. This work firstly outlines Western European and Swiss legislation for PRP products/preparations, providing key simplified information and recommendations for medical doctors seeking to implement this biological-based therapy for safe use in hospital settings, clinics, or private offices. This work secondly shows the importance of PRP-based product manufacturing standardization, which subsequently enables sound clinical evaluation of therapeutic interventions. Although the applicable legal bases provide guidelines for GMP manufacturing infrastructure and basic process design, paramount importance is set on the definition of workflows, technical specifications, and key parameters for PRP preparation and delivery. Overall, the development of simple and robust technologies and processes for PRP preparation is critical for guaranteeing the high therapeutic quality of the intervention, in collaboration with qualified GMP manufacturing platforms. Importantly, this work aims to serve as a practical tool for clinicians based in Western Europe who are willing to appropriately (i.e., administratively and technically) implement autologous PRP treatments in musculoskeletal regenerative medicine workflows, to ensure they make informed and optimal regulatory or process-based decisions.

Lyophilized Progenitor Tenocyte Extracts: Sterilizable Cytotherapeutic Derivatives with Antioxidant Properties and Hyaluronan Hydrogel Functionalization Effects

Cultured primary progenitor tenocytes in lyophilized form were previously shown to possess intrinsic antioxidant properties and hyaluronan-based hydrogel viscosity-modulating effects in vitro. The aim of this study was to prepare and functionally characterize several stabilized (lyophilized) cell-free progenitor tenocyte extracts for inclusion in cytotherapy-inspired complex injectable preparations. Fractionation and sterilization methods were included in specific biotechnological manufacturing workflows of such extracts. Comparative and functional-oriented characterizations of the various extracts were performed using several orthogonal descriptive, colorimetric, rheological, mechanical, and proteomic readouts. Specifically, an optimal sugar-based (saccharose/dextran) excipient formula was retained to produce sterilizable cytotherapeutic derivatives with appropriate functions. It was shown that extracts containing soluble cell-derived fractions possessed conserved and significant antioxidant properties (TEAC) compared to the freshly harvested cellular starting materials. Progenitor tenocyte extracts submitted to sub-micron filtration (0.22 µm) and 60Co gamma irradiation terminal sterilization (5−50 kGy) were shown to retain significant antioxidant properties and hyaluronan-based hydrogel viscosity modulating effects. Hydrogel combination products displayed important efficacy-related characteristics (friction modulation, tendon bioadhesivity) with significant (p < 0.05) protective effects of the cellular extracts in oxidative environments. Overall, the present study sets forth robust control methodologies (antioxidant assays, H2O2-challenged rheological setups) for stabilized cell-free progenitor tenocyte extracts. Importantly, it was shown that highly sensitive phases of cytotherapeutic derivative manufacturing process development (purification, terminal sterilization) allowed for the conservation of critical biological extract attributes.

Retrospectives on Three Decades of Safe Clinical Experience with Allogeneic Dermal Progenitor Fibroblasts: High Versatility in Topical Cytotherapeutic Care

Allogeneic dermal progenitor fibroblasts constitute cytotherapeutic contenders for modern cutaneous regenerative medicine. Based on advancements in the relevant scientific, technical, and regulatory fields, translational developments have slowly yet steadily led to the clinical application of such biologicals and derivatives. To set the appropriate general context, the first aim of this study was to provide a current global overview of approved cell and gene therapy products, with an emphasis on cytotherapies for cutaneous application. Notable advances were shown for North America, Europe, Iran, Japan, and Korea. Then, the second and main aim of this study was to perform a retrospective analysis on the various applications of dermal progenitor fibroblasts and derivatives, as clinically used under the Swiss progenitor cell transplantation program for the past three decades. Therein, the focus was set on the extent and versatility of use of the therapies under consideration, their safety parameters, as well as formulation options for topical application. Quantitative and illustrative data were summarized and reported for over 300 patients treated with various cell-based or cell-derived preparations (e.g., progenitor biological bandages or semi-solid emulsions) in Lausanne since 1992. Overall, this study shows the strong current interest in biological-based approaches to cutaneous regenerative medicine from a global developmental perspective, as well as the consolidated local clinical experience gathered with a specific and safe allogeneic cytotherapeutic approach. Taken together, these current and historical elements may serve as tangible working bases for the further optimization of local and modern translational pathways for the provision of topical cytotherapeutic care.

Filamented Light (FLight) Biofabrication of Highly Aligned Tissue-Engineered Constructs

Cell-laden hydrogels used in tissue engineering generally lack sufficient 3D topographical guidance for cells to mature into aligned tissues. A new strategy called filamented light (FLight) biofabrication rapidly creates hydrogels composed of unidirectional microfilament networks, with diameters on the length scale of single cells. Due to optical modulation instability, a light beam is divided optically into FLight beams. Local polymerization of a photoactive resin is triggered, leading to local increase in refractive index, which itself creates self-focusing waveguides and further polymerization of photoresin into long hydrogel microfilaments. Diameter and spacing of the microfilaments can be tuned from 2 to 30 µm by changing the coherence length of the light beam. Microfilaments show outstanding cell instructive properties with fibroblasts, tenocytes, endothelial cells, and myoblasts, influencing cell alignment, nuclear deformation, and extracellular matrix deposition. FLight is compatible with multiple types of photoresins and allows for biofabrication of centimeter-scale hydrogel constructs with excellent cell viability within seconds (<10 s per construct). Multidirectional microfilaments are achievable within a single hydrogel construct by changing the direction of FLight projection, and complex multimaterial/multicellular tissue-engineered constructs are possible by sequentially exchanging the cell-laden photoresin. FLight offers a transformational approach to developing anisotropic tissues using photo-crosslinkable biomaterials.

Nanoforming Hyaluronan-Based Thermoresponsive Hydrogels: Optimized and Tunable Functionality in Osteoarthritis Management

Hyaluronic acid (HA) constitutes a versatile chemical framework for the development of osteoarthritis pain treatment by means of injection in the joints, so-called viscosupplementation. Without appropriate physico-chemical tuning, such preparations are inherently hindered by prompt in vivo degradation, mediated by hyaluronidases and oxidative stress. To prolong hydrogel residence time and confer optimized product functionality, novel thermoresponsive nanoforming HA derivatives were proposed and characterized. Combined use of sulfo-dibenzocyclooctyne-PEG4-amine linkers and poly(N-isopropylacrylamide) in green chemistry process enabled the synthesis of HA-based polymers, with in situ obtention of appropriate viscoelastic properties. Spontaneous and reversible thermoformation of nanoparticles above 30 °C was experimentally confirmed. Lead formulations were compared to a commercially available HA-based product and shown significantly better in vitro resistance to enzymatic and oxidative degradation, required half the injection force with optimal viscoelastic hydrogel properties in equine synovial fluids. Results highlighted the vast potential of appropriately engineered HA-based systems as next-generation long-acting viscosupplementation products for osteoarthritic patients.

Combination of Hyaluronan and Lyophilized Progenitor Cell Derivatives: Stabilization of Functional Hydrogel Products for Therapeutic Management of Tendinous Tissue Disorders

Cultured progenitor cells and derivatives have been used in various homologous applications of cutaneous and musculoskeletal regenerative medicine. Active pharmaceutical ingredients (API) in the form of progenitor cell derivatives such as lysates and lyophilizates were shown to retain function in controlled cellular models of wound repair. On the other hand, hyaluronan-based hydrogels are widely used as functional vehicles in therapeutic products for tendon tissue disorders. The aim of this study was the experimental characterization of formulations containing progenitor tenocyte-derived APIs and hyaluronan, for the assessment of ingredient compatibility and stability in view of eventual therapeutic applications in tendinopathies. Lyophilized APIs were determined to contain relatively low quantities of proteins and growth factors, while being physicochemically stable and possessing significant intrinsic antioxidant properties. Physical and rheological quantifications of the combination formulas were performed after hydrogen peroxide challenge, outlining significantly improved evolutive viscoelasticity values in accelerated degradation settings. Thus, potent effects of physicochemical protection or stability enhancement of hyaluronan by the incorporated APIs were observed. Finally, combination formulas were found to be easily injectable into ex vivo tendon tissues, confirming their compatibility with further translational clinical approaches. Overall, this study provides the technical bases for the development of progenitor tenocyte derivative-based injectable therapeutic products or devices, to potentially be applied in tendinous tissue disorders.

Back to the Cradle of Cytotherapy: Integrating a Century of Clinical Research and Biotechnology-Based Manufacturing for Modern Tissue-Specific Cellular Treatments in Switzerland

Empirically studied by Dr. Brown-Séquard in the late 1800s, cytotherapies were later democratized by Dr. Niehans during the twentieth century in Western Switzerland. Many local cultural landmarks around the Léman Riviera are reminiscent of the inception of such cell-based treatments. Despite the discreet extravagance of the remaining heirs of "living cell therapy" and specific enforcements by Swiss health authorities, current interest in modern and scientifically sound cell-based regenerative medicine has never been stronger. Respective progress made in bioengineering and in biotechnology have enabled the clinical implementation of modern cell-based therapeutic treatments within updated medical and regulatory frameworks. Notably, the Swiss progenitor cell transplantation program has enabled the gathering of two decades of clinical experience in Lausanne for the therapeutic management of cutaneous and musculoskeletal affections, using homologous allogeneic cell-based approaches. While striking conceptual similarities exist between the respective works of the fathers of cytotherapy and of modern highly specialized clinicians, major and important iterative updates have been implemented, centered on product quality and risk-analysis-based patient safety insurance. This perspective article highlights some historical similarities and major evolutive differences, particularly regarding product safety and quality issues, characterizing the use of cell-based therapies in Switzerland over the past century. We outline the vast therapeutic potential to be harnessed for the benefit of overall patient health and the importance of specific scientific methodological aspects.

Hypoxic Incubation Conditions for Optimized Manufacture of Tenocyte-Based Active Pharmaceutical Ingredients of Homologous Standardized Transplant Products in Tendon Regenerative Medicine

Human fetal progenitor tenocytes (hFPT) produced in defined cell bank systems have recently been characterized and qualified as potential therapeutic cell sources in tendon regenerative medicine. In view of further developing the manufacture processes of such cell-based active pharmaceutical ingredients (API), the effects of hypoxic in vitro culture expansion on key cellular characteristics or process parameters were evaluated. To this end, multiple aspects were comparatively assessed in normoxic incubation (i.e., 5% CO₂ and 21% O₂, standard conditions) or in hypoxic incubation (i.e., 5% CO₂ and 2% O₂, optimized conditions). Experimentally investigated parameters and endpoints included cellular proliferation, cellular morphology and size distribution, cell surface marker panels, cell susceptibility toward adipogenic and osteogenic induction, while relative protein expression levels were analyzed by quantitative mass spectrometry. The results outlined conserved critical cellular characteristics (i.e., cell surface marker panels, cellular phenotype under chemical induction) and modified key cellular parameters (i.e., cell size distribution, endpoint cell yields, matrix protein contents) potentially procuring tangible benefits for next-generation cell manufacturing workflows. Specific proteomic analyses further shed some light on the cellular effects of hypoxia, potentially orienting further hFPT processing for cell-based, cell-free API manufacture. Overall, this study indicated that hypoxic incubation impacts specific hFPT key properties while preserving critical quality attributes (i.e., as compared to normoxic incubation), enabling efficient manufacture of tenocyte-based APIs for homologous standardized transplant products.