Combined surgery and chondrocyte cell-sheet transplantation improves clinical and structural outcomes in knee osteoarthritis

Laminin expression profiles of osteogenic-and chondrogenic-induced dECM sheets

Decellularized extracellular matrix sheets (dECMSs) produced by stem cells have attracted attention because they preserve the natural biological activity of the ECM to direct lineage-specific differentiation with less immunogenicity. As a core ECM protein, laminin modulates cellular phenotype and differentiation. Nevertheless, no studies thus far have explored the distribution and abundance of laminins in diverse dECMSs. Herein, we first compared the differential expression of laminins among dECMSs in osteogenic-induced medium (OI-dECMS), chondrogenic-induced medium (CI-dECMS), and standard medium (dECMS), employing a defined mass spectrometry (MS)-based proteomic analysis. In vitro, dECMSs were verified to be successfully decellularized. Cluster analysis identified a marked fluctuation in the expression of 7 laminins and 17 laminin-associated proteins in OI-dECMS vs dECMS and CI-dECMS vs dECMS. Two significantly changed pathways were selected from the KEGG pathway enrichment analysis: the FAK/ERK pathway and the PI3K/AKT pathway. Moreover, Alkaline Phosphatase (ALP) activity, Alcian blue staining, and RT-qPCR results for recellularization showed that CI-dECMS promotes chondrogenesis while OI-dECMS inhibits osteogenesis compared with dECMS. In vivo experiments were conducted to implant dECMSs in a rat osteochondral defect, demonstrating that dECMS and CI-dECMS promoted bone and cartilage repair. Furthermore, the inhibitory analysis was performed to verify the function of specific laminin isoforms modulating osteogenesis and chondrogenesis, which might be related to FAK/ERK and PI3K/AKT pathways. In summary, this study constructed dECMS, OI-dECMS, and CI-dECMS and uncovered the internal comprehensive molecular regulatory network centralized by laminins, thus proposing a biomimetic substitute for bone and cartilage regeneration.

Effective cell sheet preparation using thermoresponsive polymer brushes with various graft densities and chain lengths

Various cell sheets have been used as effective and useful cellular tissues in tissue engineering and regenerative therapy. Poly(N-isopropylacrylamide) (PNIPAAm)-modified surfaces have been investigated for effective cell sheet preparation. In this study, the effective PNIPAAm graft density and chain length of PNIPAAm brushes for various cell types were investigated. The PNIPAAm brush-grafted glass was prepared via silanization and subsequent atom transfer radical polymerization (ATRP). The density of the PNIPAAm brushes was modulated by changing the ATRP initiator and co-adsorber composition, while the PNIPAAm brush length was modulated by changing the monomer concentration in the ATRP. The hydrophilicity of the PNIPAAm brushes increased with increasing PNIPAAm brush length because long PNIPAAm brushes tended to hydrate. Fibronectin adsorption increased with decreasing PNIPAAm brush concentration because the exposed hydrophobic co-adsorber in the dilute PNIPAAm brush enhanced the adsorption of fibronectin. The cell-sheet fabrication ability was investigated using six types of PNIPAAm brushes. An endothelial cell sheet was fabricated using a dense, short PNIPAAm brush. NIH/3T3 sheets can be fabricated using three types of PNIPAAm brushes: dense-long PNIPAAm brushes, moderately dense-short PNIPAAm brushes, and dilute-long PNIPAAm brushes. MDCK cell sheets could not be prepared using the PNIPAAm brushes. A549 cell sheets were prepared using a dense-short PNIPAAm brush and moderately dense-short PNIPAAm brushes. These results indicate that the optimal PNIPAAm brush conditions for cell sheet preparation vary depending on cell type. Thus, modulation of PNIPAAm brush density and length is an effective approach for preparing target cell sheets.

Development of iPSC-derived FIX-secreting hepatocyte sheet as a novel treatment tool for hemophilia B treatment

BACKGROUND

Hemophilia B is an inherited disorder caused by a mutation in the FIX gene, which results in insufficient blood clotting factor IX (FIX) production from hepatocytes. Currently, there are no treatments for hemophilia B patients. The patients should be continuously administrated with clotting factor concentrates 2-3 times a month to prevent bleeding. Therefore, this study aimed to develop an engineered FIX-secreting hepatocyte sheet that can release FIX for an extended period. Within this study, the engineered FIX-secreting hepatocyte sheet was developed by integrating two core technologies, including a gene editing platform to generate FIX-secreting cells and cell sheet technology to improve cell delivery efficacy.

METHODS

The human FIX gene was inserted into the APOC3 site of iPSCs by CRISPR/Cas9, which secretes the target protein after differentiation into hepatocytes. FIX-secreting hepatocyte sheets were obtained by temperature-responsive polymer grafted cell culture dishes (TRCD). Immunohistochemical and functional tests were performed for hepatocyte-like cells differentiated from FIX KI-iPSCs and wild-type iPSCs (WT-iPSCs). After validating the functional activity and secretion of FIX protein, the engineered hepatocyte-like cell sheets were transplanted to NOD/SCID mice for the in vivo experiments.

RESULTS

The insertion of the human FIX gene into the APOC3 site demonstrated a significant increase in FIX secretion in hepatocyte-like cells differentiated from FIX KI-iPSCs compared with those obtained from WT-iPSCs. Among the iPSCs to hepatocyte differentiation stages, the hepatic endoderm stage was most suitable for seeding the cells on TRCD and generating cell sheets by temperature changes from 37oC to room temperature when the hepatocyte-like cells have reached maturity. The engineered FIX-secreting cell sheets showed intensive expression of the FIX proteins without losing hepatocyte morphology for 20 days. Furthermore, an in vivo study showed that engineered FIX-secreting cell sheets retained their FIX secretion functions for two weeks, whereas single-cell injected traditionally were barely detected in the experimental animals.

CONCLUSIONS

The engineered FIX-secreting cell sheets fabricated from functionally improved iPSCs with practical cell delivery tools could be a promising tool for clinically treating Hemophilia B.

Differentiated and Untreated Juvenile Chondrocyte Sheets Regenerate Cartilage Similarly In Vivo

Osteoarthritis, a degenerative disease of articular cartilage and the leading cause of disability, is preceded by acute cartilage injury in a significant proportion of cases. Current auto- and allograft interventions are limited by supply and variability in therapeutic efficacy, prompting interest in tissue engineering solutions. Cell sheet tissue engineering, a scaffold-free regenerative technique, has shown promise in preclinical and clinical trials across various cell types and diseases. Polydactyly-derived juvenile cartilage-derived chondrocyte (JCC) sheets from juvenile patients are a potent cell source for developing allogeneic therapies. JCC sheets have proven safe and effective in animal models and as an add-on therapy in a recent clinical cartilage repair study. However, JCC ex vivo expansion leads to de-differentiation, contributing to long healing times. This study hypothesized that in vitro differentiation of JCC sheets into hyaline-like cartilage constructs could accelerate cartilage regeneration without compromising implant integration. To this end, sheet integration, maturation, and healing of conventionally prepared vs. differentiated JCC sheets were compared in an established nude rat focal chondral defect model. Differentiated JCC sheets exhibit mature cartilage phenotypes prior to transplant. Both conventional and differentiated JCC sheets are reliably transplanted without additional fixation. Histological evaluation reveals that both transplant groups produced equivalent neocartilage regeneration, filling defects with mature hyaline cartilage at 2- and 4-weeks post-transplant. Notably, differentiated JCC sheets respond to in vivo signals, undergoing matrix remodeling and integration with adjacent and subchondral tissue. Given equivalent healing outcomes, the future utility of in vitro JCC sheet predifferentiation from other JCC donors with different healing capacities should be balanced against their increased culture costs over conventional sheets.

Temperature-modulated separation of vascular cells using thermoresponsive-anionic block copolymer-modified glass

Introduction

Vascular tissue engineering is a key technology in the field of regenerative medicine. In tissue engineering, the separation of vascular cells without cell modification is required, as cell modifications affect the intrinsic properties of the cells. In this study, we have developed an effective method for separating vascular cells without cell modification, using a thermoresponsive anionic block copolymer.

Methods

A thermoresponsive anionic block copolymer, poly(acrylic acid)-b-poly(N-isopropylacryl-amide) (PAAc-b-PNIPAAm), with various PNIPAAm segment lengths, was prepared in two steps: atom transfer radical polymerization and subsequent deprotection. Normal human umbilical vein endothelial cells (HUVECs), normal human dermal fibroblasts, and human aortic smooth muscle cells (SMCs) were seeded onto the prepared thermoresponsive anionic block copolymer brush-modified glass. The adhesion behavior of cells on the copolymer brush was observed at 37 °C and 20 °C.

Results

A thermoresponsive anionic block copolymer, poly(acrylic acid)-b-poly(N-isopropylacrylamide) (PAAc-b-PNIPAAm), with various PNIPAAm segment lengths was prepared. The prepared copolymer-modified glass exhibited anionic properties attributed to the bottom PAAc segment of the copolymer brush. On the PAAc-b-PNIPAAm, which had a moderate PNIPAAm length, a high adhesion ratio of HUVECs and low adhesion ratio of SMCs were observed at 37 °C. By reducing temperature from 37 °C to 20 °C, the adhered HUVECs were detached, whereas the SMCs maintained adhesion, leading to the recovery of purified HUVECs by changing the temperature.

Conclusions

The prepared thermoresponsive anionic copolymer-modified glass could be used to separate HUVECs and SMCs by changing the temperature without modifying the cell surface. Therefore, the developed cell separation method will be useful for vascular tissue engineering.

Porosity dominates over microgel stiffness for promoting chondrogenesis in zwitterionic granular hydrogels

Granular hydrogels comprised of jammed, crosslinked microgels offer great potential as biomaterial scaffolds for cell-based therapies, including for cartilage tissue regeneration. As stiffness and porosity of hydrogels affect the phenotype of encapsulated cells and the extent of tissue regeneration, the design of tunable granular hydrogels to control and optimize these parameters is highly desirable. We hypothesized that chondrogenesis could be modulated using a granular hydrogel platform based on biocompatible, zwitterionic materials with independent intra- and inter-microgel crosslinking mechanisms. Microgels are made with mechanical fragmentation of photocrosslinked zwitterionic carboxybetaine acrylamide (CBAA) and sulfobetaine methacrylate (SBMA) hydrogels, and secondarily crosslinked in the presence of cells using horseradish peroxide (HRP) to produce cell-laden granular hydrogels. We varied the intra-microgel crosslinking density to produce microgels with varied stiffnesses (1-3 kPa) and swelling properties. These microgels, when resuspended at the same weight fraction and secondarily crosslinked, resulted in granular hydrogels with distinct porosities (5-40%) due to differing swelling properties. The greatest extent of chondrogenesis was achieved in scaffolds with the highest microgel stiffness and highest porosity. However, when scaffold porosity was kept constant and just microgel stiffness varied, cell phenotype and chondrogenesis were similar across scaffolds. These results indicate the dominant role of granular scaffold porosity on chondrogenesis, whereas microgel stiffness appears to play a relatively minor role. These observations are in contrast to cells encapsulated within conventional bulk hydrogels, where stiffness has been shown to significantly affect chondrocyte response. In summary, we introduce chemically-defined, zwitterionic biomaterials to fabricate versatile granular hydrogels allowing for tunable scaffold porosity and microgel stiffness to study and influence chondrogenesis.

Reduced Cell Migration in Human Chondrocyte Sheets Increases Tissue Stiffness and Cartilage Protein Production

BACKGROUND

Chondrogenic differentiation medium (CDM) is usually used to maintain chondrogenic activity during chondrocyte sheet production. However, tissue qualities remain to be determined as to what factors improve cell functions. Moreover, the relationship between CDM and cell migration proteins has not been reported.

METHOD

In this study, the effect of CDM on the behavior of chondrocyte sheets was investigated. Structural analysis, mechanical testing and proteomics were performed to observe tissue qualities. The relationship between CDM and cell migration proteins were investigated using time-lapse observations and bioinformatic analysis.

RESULTS

During 48 h, CDM affected the chondrocyte behaviors by reducing cell migration. Compared to the basal medium, CDM impacted the contraction of monolayered chondrocyte sheets. At day 7, the contracted sheets increased tissue thickness and improved tissue stiffness. Cartilage specific proteins were also upregulated. Remarkedly, the chondrocyte sheets in CDM displayed downregulated proteins related to cell migration. Bioinformatic analysis revealed that TGFβ1 was shown to be associated with cartilage functions and cell migration. Pathway analysis of chondrocyte sheets in CDM also revealed the presence of a TGFβ pathway without activating actin production, which might be involved in synthesizing cartilage-specific proteins. Cell migration pathway showed MAPK signaling in both cultures of the chondrocyte sheets.

CONCLUSION

Reduced cell migration in the chondrocyte sheet affected the tissue quality. Using CDM, TGFβ1 might trigger cartilage protein production through the TGFβ pathway and be involved in cell migration via the MAPK signaling pathway. Understanding cell behaviors and their protein expression would be beneficial for developing high-quality tissue-engineered cartilage.

Zwitterionic Granular Hydrogel for Cartilage Tissue Engineering

Zwitterionic hydrogels have high potential for cartilage tissue engineering due to their ultra-hydrophilicity, nonimmunogenicity, and superior antifouling properties. However, their application in this field has been limited so far, due to the lack of injectable zwitterionic hydrogels that allow for encapsulation of cells in a biocompatible manner. Herein, a novel strategy is developed to engineer cartilage employing zwitterionic granular hydrogels that are injectable, self-healing, in situ crosslinkable and allow for direct encapsulation of cells with biocompatibility. The granular hydrogel is produced by mechanical fragmentation of bulk photocrosslinked hydrogels made of zwitterionic carboxybetaine acrylamide (CBAA), or a mixture of CBAA and zwitterionic sulfobetaine methacrylate (SBMA). The produced microgels are enzymatically crosslinkable using horseradish peroxidase, to quickly stabilize the construct, resulting in a microporous hydrogel. Encapsulated human primary chondrocytes are highly viable and able to proliferate, migrate, and produce cartilaginous extracellular matrix (ECM) in the zwitterionic granular hydrogel. It is also shown that by increasing hydrogel porosity and incorporation of SBMA, cell proliferation and ECM secretion are further improved. This strategy is a simple and scalable method, which has high potential for expanding the versatility and application of zwitterionic hydrogels for diverse tissue engineering applications.

A Review of Current Approaches to Pain Management in Knee Osteoarthritis with a Focus on Italian Clinical Landscape

The global cases of knee osteoarthritis (KOA) are projected to increase by 74.9% by 2050. Currently, over half of patients remain dissatisfied with their pain relief. This review addresses unmet needs for moderate-to-severe KOA pain; it offers evidence and insights for improved management. Italian experts from the fields of rheumatology, physical medicine and rehabilitation, orthopedics, primary care, and pain therapy have identified several key issues. They emphasized the need for standardized care protocols to address inconsistencies in patient management across different specialties. Early diagnosis is crucial, as cartilage responds better to early protective and structural therapies. Faster access to physiatrist evaluation and reimbursement for physical, rehabilitative, and pharmacological treatments, including intra-articular (IA) therapy, could reduce access disparities. Concerns surround the adverse effects of oral pharmacological treatments, highlighting the need for safer alternatives. Patient satisfaction with corticosteroids and hyaluronic acid-based IA therapies reduces over time and there is no consensus on the optimal IA therapy protocol. Surgery should be reserved for severe symptoms and radiographic KOA evidence, as chronic pain post-surgery poses significant societal and economic burdens. The experts advocate for a multidisciplinary approach, promoting interaction and collaboration between specialists and general practitioners, to enhance KOA care and treatment consistency in Italy.

Human platelet lysate-cultured adipose-derived stem cell sheets promote angiogenesis and accelerate wound healing via CCL5 modulation

BACKGROUND

A rising population faces challenges with healing-impaired cutaneous wounds, often leading to physical disabilities. Adipose-derived stem cells (ASCs), specifically in the cell sheet format, have emerged as a promising remedy for impaired wound healing. Human platelet lysate (HPL) provides an attractive alternative to fetal bovine serum (FBS) for culturing clinical-grade ASCs. However, the potential of HPL sheets in promoting wound healing has not been fully investigated. This study aimed to explore the anti-fibrotic and pro-angiogenic capabilities of HPL-cultured ASC sheets and delve into the molecular mechanism.

METHODS

A rat burn model was utilized to evaluate the efficacy of HPL-cultured ASC sheets in promoting wound healing. ASC sheets were fabricated with HPL, and those with FBS were included for comparison. Various analyses were conducted to assess the impact of HPL sheets on wound healing. Histological examination of wound tissues provided insights into aspects such as wound closure, collagen deposition, and overall tissue regeneration. Immunofluorescence was employed to assess the presence and distribution of transplanted ASCs after treatment. Further in vitro studies were conducted to decipher the specific factors in HPL sheets contributing to angiogenesis.

RESULTS

HPL-cultured ASC sheets significantly accelerated wound closure, fostering ample and organized collagen deposition in the neo-dermis. Significantly more retained ASCs were observed in wound tissues treated with HPL sheets compared to the FBS counterparts. Moreover, HPL sheets mitigated macrophage recruitment and decreased subsequent wound tissue fibrosis in vivo. Immunohistochemistry also indicated enhanced angiogenesis in the HPL sheet group. The in vitro analyses showed upregulation of C-C motif chemokine ligand 5 (CCL5) and angiogenin in HPL sheets, including both gene expression and protein secretion. Culturing endothelial cells in the conditioned media compared to media supplemented with CCL5 or angiogenin suggested a correlation between CCL5 and the pro-angiogenic effect of HPL sheets. Additionally, through neutralizing antibody experiments, we further validated the crucial role of CCL5 in HPL sheet-mediated angiogenesis in vitro.

CONCLUSIONS

The present study underscores CCL5 as an essential factor in the pro-angiogenic effect of HPL-cultured ASC sheets during the wound healing process. These findings highlight the potential of HPL-cultured ASC sheets as a promising therapeutic option for healing-impaired cutaneous wounds in clinical settings. Furthermore, the mechanism exploration yields valuable information for optimizing regenerative strategies with ASC products.

BRIEF ACKNOWLEDGMENT

This research was supported by the National Science and Technology Council, Taiwan (NSTC112-2321-B-002-018), National Taiwan University Hospital (111C-007), and E-Da Hospital-National Taiwan University Hospital Joint Research Program (111-EDN0001, 112-EDN0002).

Long-term prognosis and DNA damage status after oral mucosal epithelial cell sheet transplantation following esophageal endoscopic submucosal dissection for squamous cell carcinoma: A case series

Autologous oral mucosal epithelial cell sheet (AOMECS) transplantation has recently been applied in human patients to prevent postprocedural stenosis following endoscopic submucosal dissection (ESD) for esophageal squamous cell carcinoma. However, the long-term safety of AOMECS transplantation remains unclear. We evaluated the long-term outcomes of 10 patients who participated in a clinical trial of AOMECS transplantation after esophageal ESD. Additionally, we assessed the local DNA damage response in the esophageal epithelium using p53 binding protein 1 (53BP1) immunofluorescence in post-AOMECS biopsy specimens. The median follow-up period was 118.5 months (range: 46-130 months). Two patients developed primary esophageal cancer near the AOMECS site and successfully underwent additional ESD. One patient developed lymph node metastasis and underwent chemotherapy. None of the patients died from the original disease, although one patient died from unrelated causes. The rate of abnormal 53BP1 nuclear foci, indicative of increased genome instability, increased with the progression of neoplasia in patients post AOMECS. Our case series suggests that AOMECS transplantation provides an acceptable long-term prognosis and 53BP1 foci may serve as a useful marker for assessing DNA instability in the post-AOMECS esophageal epithelium.

bFGF-releasing biodegradable nanoparticles for effectively engrafting transplanted hepatocyte sheet

Hepatic tissue engineering has been applied for the treatment of intractable liver diseases, and hepatocyte sheets are promising for this purpose. However, hepatocyte sheets have poor survival after transplantation because of their high metabolic activity. In this study, we aimed to develop basic fibroblast growth factor (bFGF)-releasing nanoparticles to prolong the survival of hepatocyte sheets after transplantation. The nanoparticles were prepared by electrospraying a bFGF-dispersed poly(D,l-lactide-co-glycolide) emulsion. bFGF-loaded PLGA nanoparticles can be developed by optimizing the applied electrospray voltage and the oil:water ratio of the emulsion. The prepared nanoparticles exhibited prompt release at the initial duration and continuous gradual release at the subsequent duration. Hepatocyte sheet engraftment was evaluated by transplanting hepatocyte sheets containing the prepared nanoparticles into rats. The hepatocyte sheets with the prepared nanoparticles exhibited longer survival than those without the bFGF nanoparticles or solution owing to the local and continuous release of bFGF from the nanoparticles and the subsequent enhanced angiogenesis at the transplantation site. These results indicated that the prepared bFGF-releasing nanoparticles can enhance the efficiency of hepatocyte sheet transplantation. The developed bFGF-releasing nanoparticles would be useful for the transplantation of cellular tissue with post-transplantation survival challenges.

Ionically annealed zwitterionic microgels for bioprinting of cartilaginous constructs

Foreign body response (FBR) is a pervasive problem for biomaterials used in tissue engineering. Zwitterionic hydrogels have emerged as an effective solution to this problem, due to their ultra-low fouling properties, which enable them to effectively inhibit FBRin vivo. However, no versatile zwitterionic bioink that allows for high resolution extrusion bioprinting of tissue implants has thus far been reported. In this work, we introduce a simple, novel method for producing zwitterionic microgel bioink, using alginate methacrylate (AlgMA) as crosslinker and mechanical fragmentation as a microgel fabrication method. Photocrosslinked hydrogels made of zwitterionic carboxybetaine acrylamide (CBAA) and sulfobetaine methacrylate (SBMA) are mechanically fragmented through meshes with aperture diameters of 50 and 90µm to produce microgel bioink. The bioinks made with both microgel sizes showed excellent rheological properties and were used for high-resolution printing of objects with overhanging features without requiring a support structure or support bath. The AlgMA crosslinker has a dual role, allowing for both primary photocrosslinking of the bulk hydrogel as well as secondary ionic crosslinking of produced microgels, to quickly stabilize the printed construct in a calcium bath and to produce a microporous scaffold. Scaffolds showed ∼20% porosity, and they supported viability and chondrogenesis of encapsulated human primary chondrocytes. Finally, a meniscus model was bioprinted, to demonstrate the bioink's versatility at printing large, cell-laden constructs which are stable for furtherin vitroculture to promote cartilaginous tissue production. This easy and scalable strategy of producing zwitterionic microgel bioink for high resolution extrusion bioprinting allows for direct cell encapsulation in a microporous scaffold and has potential forin vivobiocompatibility due to the zwitterionic nature of the bioink.

Cell Therapy Approaches for Articular Cartilage Regeneration

Articular cartilage is a common cartilage type found in a multitude of joints throughout the human body. However, cartilage is limited in its regenerative capacity. A range of methods have been employed to aid adults under the age of 45 with cartilage defects, but other cartilage pathologies such as osteoarthritis are limited to non-steroidal anti-inflammatory drugs and total joint arthroplasty. Cell therapies and synthetic biology can be utilized to assist not only cartilage defects but have the potential as a therapeutic approach for osteoarthritis as well. In this review, we will cover current cell therapy approaches for cartilage defect regeneration with a focus on autologous chondrocyte implantation and matrix autologous chondrocyte implantation. We will then discuss the potential of stem cells for cartilage repair in osteoarthritis and the use of synthetic biology to genetically engineer cells to promote cartilage regeneration and potentially reverse osteoarthritis.

Research and publication trends on knee osteoarthritis and cellular senescence: a bibliometric analysis

Background: Cellular senescence is associated with age-related pathological changes, senescent cells promote the development of knee osteoarthritis. A better understanding between knee osteoarthritis and cellular senescence may enhance the effectiveness of therapies that aim to slow or stop the progression of this disease. Purpose: This study aimed to systematically analyze and visualize the publication trends, research frontiers and current research hotspots of knee osteoarthritis and cellular senescence by using bibliometrics. Methods: The publication search was performed on the Web of Science Core Collection database for documents published from 1992 to 2023. VOSviewer, Citespace, R package Bibliometrix and Microsoft Office Excel were used to study the characteristics of the publications. The publication number, countries, institutions, authors, journals, citations and co-citations, keywords were analyzed. Results: A total of 1,074 publications were analyzed, with an average annual growth rate of 29.89%. United States accounted for the biggest contributor, ranked first in publications and citations. Publications of this field were published in 420 journals, OSTEOARTHRITIS and CARTILAGE was the most influential. A total of 5,657 authors contributed to this research. The most productive author was Lotz, MK (n = 31, H-index = 22, Total citation = 2,619), followed by Loeser, R.F (n = 16, H-index = 14, Total citation = 2,825). However, the collaboration between authors was relatively weak. Out of the 1,556 institutions involved, 60% were from the United States. Scripps Research ranked first with 25 papers and a total of 2,538 citations. The hotspots of this field had focused on the pathomechanisms (e.g., expression, inflammation, apoptosis, autophagy, oxidative stress) and therapeutics (e.g., stem cell, platelet-rich plasma, transplantation, autologous chondrocytes, repair), and the exploration of Senolytics might be the important direction of future research. Conclusion: Research on the cross field of knee osteoarthritis and cellular senescence is flourishing. Age-related pathomechanism maps of various cells in the joint and the targeted medicines for the senescent cells may be the future trends. This bibliometric study provides a comprehensive analysis of this cross field and new insights into future research.

Fabrication of shape-designable cartilage from human induced pluripotent stem cell-derived chondroprogenitors using a cell self-aggregation technique

With the advancement of tissue engineering technologies, implantable materials have been developed for use in facial plastic surgery, including auriculoplasty and rhinoplasty. Tissue-engineered cartilage comprising only cells and cell-produced extracellular matrix is considered valuable as there is no need to consider problems associated with scaffold absorption or immune responses commonly related to conventional artificial materials. However, it is exceedingly difficult to produce large-sized complex shapes of cartilage without the use of scaffolds. In this study, we describe the production of shape-designable cartilage using a novel cell self-aggregation technique (CAT) and chondroprogenitor cells derived from human induced pluripotent stem cells as the source. The method described does not require special equipment such as bio-3D printers, and the produced tissue can be induced into well-matured cartilage with abundant cartilage matrixin vitro. Using CAT, we were able to generate cartilage in the form of rings or tubes with adjustable inner diameter and curvature, over a range of several centimeters, without the use of scaffolds. Thein vitrofabrication of shape-designable cartilage using CAT is a promising development in facial plastic surgery.

Cardiac cell sheet engineering for regenerative medicine and tissue modeling

Stem cell biology and tissue engineering are essential techniques for cardiac tissue construction. We have succeeded in fabricating human cardiac tissue using the mass production technology of human iPS cell-derived cardiomyocytes and cell sheet engineering, and we are developing regenerative medicine and tissue models to apply this tissue to heart disease research. Cardiac tissue fabrication and tissue functional evaluation technologies for contractile and electrophysiological function are indispensable, which lead to the functional improvement of bioengineered human cardiac tissue.

Fabrication Strategies for Engineered Thin Membranous Tissues

Thin membranous tissues (TMTs) are anatomical structures consisting of multiple stratified cell layers, each less than 100 μm in thickness. While these tissues are small in scale, they play critical roles in normal tissue function and healing. Examples of TMTs include the tympanic membrane, cornea, periosteum, and epidermis. Damage to these structures can be caused by trauma or congenital disabilities, resulting in hearing loss, blindness, dysfunctional bone development, and impaired wound repair, respectively. While autologous and allogeneic tissue sources for these membranes exist, they are significantly limited by availability and patient complications. Tissue engineering has therefore become a popular strategy for TMT replacement. However, due to their complex microscale architecture, TMTs are often difficult to replicate in a biomimetic manner. The critical challenge in TMT fabrication is balancing fine resolution with the ability to mimic complex target tissue anatomy. This Review reports existing TMT fabrication strategies, their resolution and material capabilities, cell and tissue response, and the advantages and disadvantages of each technique.

Thermoresponsive mixed polymer brush to effectively control the adhesion and separation of stem cells by altering temperature

During the last few decades, thermoresponsive materials for modulating cell adhesion have been investigated for the application of tissue engineering. In this study, we developed thermoresponsive mixed polymer brushes consisting of poly(N-isopropylacrylamide) (PNIPAAm) and poly(N,N-dimethylaminopropylacrylamide) (PDMAPAAm). The mixed polymer brushes were prepared on a glass substrate via the reversible addition-fragmentation chain transfer polymerization of DMAPAAm and subsequent atom transfer radical polymerization of NIPAAm. The mixed polymer brushes grafted to glass exhibited increased cationic properties by increasing the grafted PDMAPAAm length. The shrinking and extension of PNIPAAm exposed and concealed PDMAPAAm, respectively, indicating that the surface cationic properties can be controlled by changing the temperature. At 37 ​°C, the prepared mixed polymer brushes enhanced cell adhesion through their electrostatic interactions with cells. They also exhibited various thermoresponsive adhesion and detachment properties using various types of cells, such as mesenchymal stem cells. Temperature-controlled cell adhesion and detachment behavior differed between cell types. Using the prepared mixed polymer brush, we separated MSCs from adipocytes and HeLa cells by simply changing the temperature. Thus, the thermoresponsive mixed polymer brushes may be used to separate mesenchymal stem cells from their differentiated or contaminant cells by altering the temperature.

The preclinical and clinical progress of cell sheet engineering in regenerative medicine

Cell therapy is an accessible method for curing damaged organs or tissues. Yet, this approach is limited by the delivery efficiency of cell suspension injection. Over recent years, biological scaffolds have emerged as carriers of delivering therapeutic cells to the target sites. Although they can be regarded as revolutionary research output and promote the development of tissue engineering, the defect of biological scaffolds in repairing cell-dense tissues is apparent. Cell sheet engineering (CSE) is a novel technique that supports enzyme-free cell detachment in the shape of a sheet-like structure. Compared with the traditional method of enzymatic digestion, products harvested by this technique retain extracellular matrix (ECM) secreted by cells as well as cell-matrix and intercellular junctions established during in vitro culture. Herein, we discussed the current status and recent progress of CSE in basic research and clinical application by reviewing relevant articles that have been published, hoping to provide a reference for the development of CSE in the field of stem cells and regenerative medicine.

Engineering of MSCs sheet for the prevention of myocardial ischemia and for left ventricle remodeling

Tissue engineering combines cell biology and material science to construct tissues or organs for disease modeling, drug testing, and regenerative medicine. The cell sheet is a newly developed tissue engineering technology that has brought about scaffold-free tissue and shows great application potential. In this review, we summarized recent progress and future possibilities in preclinical research into and clinical applications of cell sheets fabricated by differing cell types from various sources for cardiac tissue repair, and the manufacturing strategies and promising application potential of 3D cell-dense tissue constructed from cell sheets. Special attention was paid to the mechanisms of mesenchymal stem cell (MSC) sheets in the prevention of myocardial ischemia and left ventricle remodeling. Comparing MSCs sheets with other types of cell sheets and 3D cardiac tissues, engineering tissues' potential safety and effectiveness concerns were also discussed.

Orthobiologics: a review

PURPOSE

The use of biologic materials in orthopaedics (orthobiologics) has gained significant attention over the past years. To enhance the body of the related literature, this review article is aimed at summarizing these novel biologic therapies in orthopaedics and at discussing their multiple clinical implementations and outcomes.

METHODS

This review of the literature presents the methods, clinical applications, impact, cost-effectiveness, and outcomes, as well as the current indications and future perspectives of orthobiologics, namely, platelet-rich plasma, mesenchymal stem cells, bone marrow aspirate concentrate, growth factors, and tissue engineering.

RESULTS

Currently available studies have used variable methods of research including biologic materials as well as patient populations and outcome measurements, therefore making comparison of studies difficult. Key features for the study and use of orthobiologics include minimal invasiveness, great healing potential, and reasonable cost as a nonoperative treatment option. Their clinical applications have been described for common orthopaedic pathologies such as osteoarthritis, articular cartilage defects, bone defects and fracture nonunions, ligament injuries, and tendinopathies.

CONCLUSIONS

Orthobiologics-based therapies have shown noticeable clinical results at the short- and mid-term. It is crucial that these therapies remain effective and stable in the long term. The optimal design for a successful scaffold remains to be further determined.

Experimental Study on the Biological Outcome of Auricular Cartilage and Costal Cartilage at Different Time Periods After Autologous Cartilage Rhinoplasty

Since autologous cartilage is a good transplant material, it is widely used in various fields of clinical medicine. In this study, we collected clinical specimens obtained at different numbers of years after transplantation and used histologic staining to explore the post-transplantation changes in auricular cartilage and costal cartilage. A retrospective analysis was performed on patients who underwent primary autologous cartilage rhinoplasty and secondary rhinoplasty from 2017 to 2021, and the remaining autologous cartilage tissue after surgery was used for histologic testing. As time progressed after transplantation, the density of costal chondrocytes decreased first and then increased, while the secretion of type II collagen and extracellular matrix both decreased slightly. There was a clear boundary between the cartilage tissue and the surrounding connective tissue, and there was no ingrowth of blood vessels in the cartilage. Auricular cartilage showed a decrease in the integrity of the matrix edge. Moreover, local fibrosis was visible, and vascular ingrowth was observed at the edge of the cartilage. The content of type II collagen first increased and then decreased, and the cell secretion function was lower than that of normal chondrocytes. The results of the study suggest that the histologic outcome of elastic cartilage after transplantation is significantly different from that of hyaline cartilage. Moreover, costal cartilage was more stable than auricular cartilage after transplantation.

A novel chondrocyte sheet fabrication using human-induced pluripotent stem cell-derived expandable limb-bud mesenchymal cells

BACKGROUND

Cell sheet fabrication for articular cartilage regenerative medicine necessitates a large number of chondrocytes of consistent quality as a cell source. Previously, we have developed human-induced pluripotent stem cell (iPSC)-derived expandable PRRX1⁺ limb-bud mesenchymal cells (ExpLBM) with stable expansion and high chondrogenic capacity, while in this study; our ExpLBM technology was combined with cell sheet engineering to assess its potential as a stable cell source for articular cartilage regeneration.

METHODS

ExpLBM cells derived from human-induced pluripotent stem cells (hiPSCs), including 414C2 and Ff-KVs09 (HLA homozygous), were seeded onto a culture plate and two-dimensional chondrogenic induction (2-DCI) was initiated. After 2-DCI, ExpLBM-derived chondrocytes were stripped and transferred to temperature-responsive culture inserts and the chondrocyte sheets were histologically examined or transplanted into osteochondral knee defects of immunodeficient rats.

RESULTS

Immunohistochemistry revealed that ExpLBM-derived cell sheets were positive for Safranin O, COL2, and ACAN but that they were negative for COL1 and RUNX2. Furthermore, the engrafted tissues in osteochondral knee defects in immunodeficient rats were stained with SafO, human VIMENTIN, ACAN, and COL2.

CONCLUSIONS

The present study is the first to report the chondrocyte sheet fabrication with hiPSC-derived cell source. hiPSC-derived ExpLBM would be a promising cell source for cell sheet technology in articular cartilage regenerative medicine.

Tissue engineering in growth plate cartilage regeneration: Mechanisms to therapeutic strategies

The repair of growth plate injuries is a highly complex process that involves precise spatiotemporal regulation of multiple cell types. While significant progress has been made in understanding the pathological mechanisms underlying growth plate injuries, effectively regulating this process to regenerate the injured growth plate cartilage remains a challenge. Tissue engineering technology has emerged as a promising therapeutic approach for achieving tissue regeneration through the use of functional biological materials, seed cells and biological factors, and it is now widely applied to the regeneration of bone and cartilage. However, due to the unique structure and function of growth plate cartilage, distinct strategies are required for effective regeneration. Thus, this review provides an overview of current research on the application of tissue engineering to promote growth plate regeneration. It aims to elucidates the underlying mechanisms by which tissue engineering promotes growth plate regeneration and to provide novel insights and therapeutic strategies for future research on the regeneration of growth plate.

Cell Sheet Technology as an Engineering-Based Approach to Bone Regeneration

Bone defects that are congenital or the result of infection, malignancy, or trauma represent a challenge to the global healthcare system. To address this issue, multiple research groups have been developing novel cell sheet technology (CST)-based approaches to promote bone regeneration. These methods hold promise for use in regenerative medicine because they preserve cell-cell contacts, cell-extracellular matrix interactions, and the protein makeup of cell membranes. This review introduces the concept and preparation system of the cell sheet (CS), explores the application of CST in bone regeneration, highlights the current states of the bone regeneration via CST, and offers perspectives on the challenges and future research direction of translating current knowledge from the lab to the clinic.

Polydactyly-derived allogeneic chondrocyte cell-sheet transplantation with high tibial osteotomy as regenerative therapy for knee osteoarthritis

Allogeneic cell therapies are not fully effective in treating osteoarthritis of the knee (OAK). We recently reported that transplantation of autologous chondrocyte cell-sheets along with open-wedge high tibial osteotomy promoted hyaline cartilage repair in humans. Here we describe our regenerative therapy for OAK using polydactyly-derived allogeneic chondrocyte cell-sheets (PD sheets) and temperature-responsive culture inserts. Ten patients with OAK and cartilage defects categorized arthroscopically as Outerbridge grade III or IV received the therapy. Cartilage viscoelasticity and thickness were assessed before and after transplantation. Arthroscopic biopsies obtained 12 months after transplantation were analyzed histologically. Gene expression was analyzed to evaluate the PD sheets. In this small initial longitudinal series, PD sheet transplantation was effective in treating OAK, as indicated by changes in cartilage properties. Gene marker sets in PD sheets may predict outcomes after therapy and provide markers for the selection of donor cells. This combined surgery may be an ideal regenerative therapy with disease-modifying effects in OAK patients.

Rapid and chronological expression of angiogenetic genes is a major mechanism involved in cell sheet transplantation in a rat gastric ulcer model

Introduction

Cell sheet technology has been applied in the treatment of patients with severe cardiac failure. Although the paracrine effect of cell sheets accelerating angiogenesis is thought to be the intrinsic mechanism for improvement of cardiac function, little is known about how a cell sheet would function in the abdomen.

Methods

We used acetic acid-induced gastric ulcer rat model to elucidate the mechanisms of myoblast sheet transplantation in the abdomen. Myoblast sheet was implanted onto the serosal side of the gastric ulcer and the effect of sheet transplantation was analyzed. The maximal diameter of the ulcer and the changes in the gene expression of various growth factors in transplanted site was analyzed. The progenitor marker CD34 was also examined by immunohistochemistry.

Results

Cell sheet transplantation accelerated the ulcer healing. qPCR showed that angiogenic growth factors were significantly upregulated around the ulcer in the transplantation group. In addition, at first, HIF-1a and SDF-1 continued to increase from 3 h after transplantation to 72 h, then VEGF increased significantly after 24 h with a slight delay. An immunohistochemical analysis showed a statistically significant increase in CD34 positivity in the tissue around the ulcer in the transplantation group.

Conclusion

Myoblast sheet secreted various growth factors and cytokines immediately after transplantation onto the serosal side of artificial ulcer in the abdomen. Autonomous secretion, resulting in the time-dependent and well-orchestrated gene expression of various growth factors, plays a crucial role in the cell sheet function. Cell sheet transplantation is expected to be useful to support angiogenesis of the ischemic area in the abdominal cavity.

Thermoresponsive block copolymer brush for temperature-modulated hepatocyte separation

Hepatic tissue engineering may be an effective approach for the treatment of liver disease; however, its practical application requires hepatic cell separation technologies that do not involve cell surface modification and maintain cell activity. In this study, we developed hepatocyte cell separation materials using a thermoresponsive polymer and a polymer with high affinity to hepatocytes. A block copolymer of poly(N-p-vinylbenzyl-O-β-D-galactopyranosyl-(1→4)-D-gluconamide) (PVLA) and poly(N-isopropylacrylamide) (PNIPAAm) [PVLA-b-PNIPAAm] was prepared through two steps of atom transfer radical polymerization. On the prepared PVLA-b-PNIPAAm brush, HepG2 cells (model hepatocytes) adhered at 37 °C and detached at 20 °C, attributed to the temperature-modulated affinity between PVLA and HepG2. Cells from the immortalized human hepatic stellate cell line (TWNT-1) did not adhere to the copolymer brush, and RAW264.7 cells (mouse macrophage; model Kupffer cells) adhered to the copolymer brush, regardless of temperature. Using the difference in cell adhesion properties on the copolymer brush, temperature-modulated cell separation was successfully demonstrated. A mixture of HepG2, RAW264.7, and TWNT-1 cells was seeded on the copolymer brush at 37 °C for adherence. By reducing the temperature to 20 °C, adhered HepG2 cells were selectively recovered with a purity of approximately 85% and normal activity. In addition, induced pluripotent stem (iPS) cell-derived hepatocytes adhered on the PVLA-b-PNIPAAm brush at 37 °C and detached from the copolymer brush at 20 °C, whereas the undifferentiated iPS cells did not adhere, indicating that the prepared PVLA-b-PNIPAAm brush could be utilized to separate hepatocyte differentiated and undifferentiated cells. These results indicated that the newly developed PVLA-b-PNIPAAm brush can separate hepatic cells from contaminant cells by temperature modulation, without affecting cell activity or modifying the cell surface. Thus, the copolymer brush is expected to be a useful separation tool for cell therapy and tissue engineering using hepatocytes.

Immunomodulatory potential of secretome from cartilage cells and mesenchymal stromal cells in an arthritic context: From predictive fiction toward reality

The purpose of the present study is to predict by bioinformatics the activity of the extracellular vesicle (EV)-embedded micro RNA (miRNAs) secreted by cartilage cells (CCs), adipose tissue-derived- (ASCs), and bone marrow-derived stem cells (BMSCs) and verify their immunomodulatory potential supporting our bioinformatics findings to optimize the autologous cell-based therapeutic strategies for osteoarthritis (OA) management. Cells were isolated from surgical waste tissues of three patients who underwent total hip replacement, expanded and the EVs were collected. The expression of EV-embedded miRNA was evaluated with the QuantStudio 12 K Flex OpenArray^® platform. Mientournet and ingenuity pathway analysis (IPA) were used for validated target prediction analysis and to identify miRNAs involved in OA and inflammation. Cells shared the expression of 325 miRNAs embedded in EVs and differed for the expression of a small number of them. Mienturnet revealed no results for miRNAs selectively expressed by ASCs, whereas miRNA expressed by CCs and BMSCs were putatively involved in the modulation of cell cycle, senescence, apoptosis, Wingless and Int-1 (Wnt), transforming growth factor beta (TGFβ), vascular endothelial growth factor (VEGF), Notch, Hippo, tumor necrosis factor alpha (TNFα), interleukin 1 beta (IL-1β), insulin like growth factor 1 (IGF-1), RUNX family transcription factor 2 (RUNX2), and endochondral ossification pathways. Cartilage homeostasis, macrophages and T cells activity and inflammatory mediators were identified by IPA as targets of the miRNAs found in all the cell populations. Co-culture tests on macrophages and T cells confirmed the immuno-modulatory ability of CCs, ASCs, and BMSCs. The study findings support the rationale behind the use of cell-based therapy for the treatment of OA.

Strategy of a cell-derived extracellular matrix for the construction of an osteochondral interlayer

Osteochondral defects pose an enormous challenge due to the lack of an effective repair strategy. To tackle this issue, the importance of a calcified cartilage interlayer (CCL) in modulating osteochondral regeneration should be valued. Herein, we proposed that an extracellular matrix (ECM) derived from a suitable cell source might efficiently promote the formation of calcified cartilage. To the end, cell sheets from four kinds of cells, including bone marrow mesenchymal stem cells (BMSCs), pre-osteoblasts (MC3T3), chondrocytes (Cho), and artificially induced hypertrophic chondrocytes (HCho), were obtained by seeding the cells on electrospun fibrous meshes, followed by decellularization to prepare decellularized ECMs (D-ECMs) for BMSC re-seeding and differentiation studies. For cell proliferation, the BMSC-derived D-ECM exhibited the strongest promotion effect. For inducing the hypertrophic phenotype of re-seeded BMSCs, both the BMSC-derived and HCho-derived D-ECMs demonstrated stronger capacity in up-regulating the depositions of related proteins and the expressions of marker genes, as compared to the MC3T3-derived and Cho-derived D-ECMs. Accordingly, from the histological results of their subcutaneous implantation in rats, both the BMSC-derived and HCho-derived D-ECMs displayed obvious Masson's trichrome and Safranin-O/Fast-Green staining colors simultaneously, representing the characteristics related to osteogenesis and chondrogenesis. Differently, MC3T3-derived and Cho-derived D-ECMs were mainly detected during the osteogenic or chondrogenic expression, respectively. These findings confirmed that the BMSC-derived D-ECM could induce hypertrophic chondrocytes, though being a little inferior to the HCho-derived D-ECM. Overall, the BMSC-derived D-ECM could be a potential material in constructing the interlayer for osteochondral tissue engineering scaffolds to improve the regeneration efficiency.

Genetic Disorders of the Extracellular Matrix: From Cell and Gene Therapy to Future Applications in Regenerative Medicine

Metazoans have evolved to produce various types of extracellular matrix (ECM) that provide structural support, cell adhesion, cell-cell communication, and regulated exposure to external cues. Epithelial cells produce and adhere to a specialized sheet-like ECM, the basement membrane, that is critical for cellular homeostasis and tissue integrity. Mesenchymal cells, such as chondrocytes in cartilaginous tissues and keratocytes in the corneal stroma, produce a pericellular matrix that presents optimal levels of growth factors, cytokines, chemokines, and nutrients to the cell and regulates mechanosensory signals through specific cytoskeletal and cell surface receptor interactions. Here, we discuss laminins, collagen types IV and VII, and perlecan, which are major components of these two types of ECM. We examinegenetic defects in these components that cause basement membrane pathologies such as epidermolysis bullosa, Alport syndrome, rare pericellular matrix-related chondrodysplasias, and corneal keratoconus and discuss recent advances in cell and gene therapies being developed for some of these disorders.

Novel advances in strategies and applications of artificial articular cartilage

Artificial articular cartilage (AC) is extensively applied in the repair and regeneration of cartilage which lacks self-regeneration capacity because of its avascular and low-cellularity nature. With advances in tissue engineering, bioengineering techniques for artificial AC construction have been increasing and maturing gradually. In this review, we elaborated on the advances of biological scaffold technologies in artificial AC including freeze-drying, electrospinning, 3D bioprinting and decellularized, and scaffold-free methods such as self-assembly and cell sheet. In the following, several successful applications of artificial AC built by scaffold and scaffold-free techniques are introduced to demonstrate the clinical application value of artificial AC.

Macromolecular crowding transforms regenerative medicine by enabling the accelerated development of functional and truly three-dimensional cell assembled micro tissues

Scaffold-free in vitro organogenesis exploits the innate ability of cells to synthesise and deposit their own extracellular matrix to fabricate tissue-like assemblies. Unfortunately, cell-assembled tissue engineered concepts require prolonged ex vivo culture periods of very high cell numbers for the development of a borderline three-dimensional implantable device, which are associated with phenotypic drift and high manufacturing costs, thus, hindering their clinical translation and commercialisation. Herein, we report the accelerated (10 days) development of a truly three-dimensional (338.1 ± 42.9 μm) scaffold-free tissue equivalent that promotes fast wound healing and induces formation of neotissue composed of mature collagen fibres, using human adipose derived stem cells seeded at only 50,000 cells/cm2 on an poly (N-isopropylacrylamide-co-N-tert-butylacrylamide (PNIPAM86-NTBA14) temperature-responsive electrospun scaffold and grown under macromolecular crowding conditions (50 μg/ml carrageenan). Our data pave the path for a new era in scaffold-free regenerative medicine.

Autologous chondrocyte implantation provides good long-term clinical results in the treatment of knee osteoarthritis: a systematic review

PURPOSE

To evaluate the mid- and long-term efficacy of autologous chondrocyte implantation (ACI) and matrix-assisted chondrocyte implantation (MACI) to treat patients with knee cartilage defects in the presence of osteoarthritis (OA).

METHODS

PubMed and Cochrane databases were systematically searched for studies describing the treatment of knee OA with ACI or MACI (Kellgren-Lawrence (KL) ≥ 1, minimum follow-up 36 months). Results were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines and included Lysholm, Western Ontario McMaster University and International Knee Documentation Committee scores.

RESULTS

Of the 127 full-text articles assessed for eligibility, only five studies were selected based on inclusion/exclusion criteria (2 on ACI and 3 on MACI). In both groups, the defects were mainly located at femoral level, size 2.2-15.1 cm² in the ACI and 2.0-7.6 cm² in the MACI group. ACI was mostly used for patients affected by KL I, whereas MACI for patients with KL II-IV. The data obtained from 235 patients (161 ACI, 74 MACI) showed that ACI and MACI sustained stable clinical improvements up to 11 and 15 years, respectively, with a failure rate of about 10% up to 11 years. Scarce biological details regarding chondrocyte implantation were reported.

CONCLUSIONS

ACI and MACI procedures for the treatment of knee cartilage lesions associated to OA showed long-term success and allowed delaying arthroplasty. Additional trials reporting homogenous data and precise patient characterization are needed to conduct an effective literature meta-analysis and identify the clinical relevance of these procedures.

LEVEL OF EVIDENCE

IV.

Intra-articular Injection of Mesenchymal Stem Cells After High Tibial Osteotomy in Osteoarthritic Knee: Two-Year Follow-up of Randomized Control Trial

Intra-articular injection of adipose-derived mesenchymal stem cell (ADMSC) after medial open-wedge high tibial osteotomy (MOWHTO) would be a promising disease-modifying treatment by correcting biomechanical and biochemical environment for arthritic knee with varus malalignment. However, there is a paucity of clinical evidence of the treatment. This randomized controlled trial (RCT) was aimed to assess regeneration of cartilage defect, functional improvement, and safety of intra-articular injection of ADMSCs after MOWHTO compared with MOWHTO alone for osteoarthritic knee with varus malalignment. This RCT allocated 26 patients into the MOWHTO with ADMSC-injection group (n = 13) and control (MOWHTO-alone) group (n = 13). The primary outcome was the serial changes of cartilage defect on periodic magnetic resonance imaging (MRI) evaluation using valid measurements until postoperative 24 months. Secondary outcomes were the 2-stage arthroscopic evaluation for macroscopic cartilage status and the postoperative functional improvements of patient-reported outcome measures until the latest follow-up. Furthermore, safety profiles after the treatment were evaluated. Cartilage regeneration on serial MRIs showed significantly better in the ADMSC group than in the control group. The arthroscopic assessment revealed that total cartilage regeneration was significantly better in the ADMSC group. Although it was not significant, functional improvements after the treatment showed a tendency to be greater in the ADMSC group than in the control group from 18 months after the treatment. No treatment-related adverse events, serious adverse events, and postoperative complications occurred in all cases. Concomitant intra-articular injection of ADMSCs with MOWHTO had advantages over MOWHTO alone in terms of cartilage regeneration with safety at 2-year follow-up, suggesting potential disease-modifying treatment for knee OA with varus malalignment.

Highly feasible procedure for laparoscopic transplantation of cell sheets under pneumoperitoneum in porcine model

INTRODUCTION

Cell sheet technology is one of the most successful methodologies in regenerative medicine. Various applications of cell sheets have been introduced in first-in-human studies in several clinical fields. When transplanting a cell sheet into internal organs, a relatively large incision is required for delivery due to difficulty handling the sheet. We developed a laparoscopic delivery procedure for safe and easy transplantation of cell sheets in a porcine model.

METHODS

Pneumoperitoneum was established by inflation with CO2. First, to increase the strength during handling, fibrin was sprayed onto the surface of the cell sheet, and then a myoblast sheet was placed onto the newly developed carrier. The sheets were pinched with laparoscopic forceps to insert into the abdominal cavity through the laparoscopic port. Myoblast sheets were then applied to the surface of the liver, colon, small intestine, and stomach, and procedure times were measured. At three days post transplantation, a histopathological examination was performed to confirm engraftment of the sheet. The function and engraftment were also analyzed in a duodenal endoscopic submucosal dissection (ESD) model.

RESULTS

The fibrin-processed myoblast sheet was able to be managed with conventional laparoscopic forceps without breaking. Despite the drastic change in air pressure by passing through the laparoscopic port, the sheets suffered no apparent damage. The transplantation procedure times did not markedly differ among transplant sites. A histopathological examination revealed thin-layered, desmin-positive cells at each transplant site. With transplantation following ESD, the engrafted myoblast sheets effectively prevented delayed perforation.

CONCLUSIONS

Our procedure is simple, and the system involves a carrier made of medically fit silicon, commercially available fibrin glue and conventional laparoscopic forceps. Our procedure is a powerful tool for laparoscopical cell sheet transplantation.

Bone Marrow MSC Secretome Increases Equine Articular Chondrocyte Collagen Accumulation and Their Migratory Capacities

Equine osteoarthritis (OA) leads to cartilage degradation with impaired animal well-being, premature cessation of sport activity, and financial losses. Mesenchymal stem cell (MSC)-based therapies are promising for cartilage repair, but face limitations inherent to the cell itself. Soluble mediators and extracellular vesicles (EVs) secreted by MSCs are the alternatives to overcome those limitations while preserving MSC restorative properties. The effect of equine bone marrow MSC secretome on equine articular chondrocytes (eACs) was analyzed with indirect co-culture and/or MSC-conditioned media (CM). The expression of healthy cartilage/OA and proliferation markers was evaluated in eACs (monolayers or organoids). In vitro repair experiments with MSC-CM were made to evaluate the proliferation and migration of eACs. The presence of nanosized EVs in MSC-CM was appraised with nanoparticle tracking assay and transmission electron microscopy. Our results demonstrated that the MSC secretome influences eAC phenotype by increasing cartilage functionality markers and cell migration in a greater way than MSCs, which could delay OA final outcomes. This study makes acellular therapy an appealing strategy to improve equine OA treatments. However, the MSC secretome contains a wide variety of soluble mediators and small EVs, such as exosomes, and further investigation must be performed to understand the mechanisms occurring behind these promising effects.

Application Effect of Different Concentrations of Platelet-Rich Plasma Combined with Quadriceps Training on Cartilage Repair of Knee Osteoarthritis

We investigated the application effect of different concentrations of platelet-rich plasma (PRP) combined with quadriceps training on cartilage repair of knee osteoarthritis. Data of 37 patients with knee osteoarthritis (KOA) treated in our hospital (November 2019–February 2021) were retrospectively analyzed and the patients were divided into low concentration group (LCG) (n = 12), medium concentration group (MCG) (n = 12), and high concentration group (HCG) (n = 13) according to the order of admission. All patients received quadriceps training. Three groups above received knee injection of PRP, and the platelet concentrations were 1000–1400 × 10⁹/L, 1400–1800 × 10⁹/L, and 1800–2100 × 10⁹/L, respectively. Articular cartilage thickness of the medial and lateral femur, knee joint function scores, inflammatory factor levels, and matrix metalloproteinases (MMPs) levels were compared. After treatment, compared with the MCG and HCG, articular cartilage thickness of the medial and lateral femur of the diseased side in the LCG was obviously lower (P < 0.05). At 2 months after treatment (T₃), compared with the HCG, articular cartilage thickness of the medial and lateral femur of the diseased side in the MCG was obviously higher (P < 0.05), without remarkable difference in articular cartilage thickness of the medial and lateral femur of the healthy side among three groups (P > 0.05). After treatment, compared with the LCG, knee joint function scores of the MCG and HCG were obviously better (P < 0.001). Compared with the HCG, the knee function score at T₃ in the MCG was obviously better (P < 0.001). After treatment, compared with the LCG, inflammatory factor levels and levels of MMPs in the MCG and HCG were obviously lower (P < 0.05). Compared with the HCG, inflammatory factor levels and levels of MMPs at T₃ in the MCG were obviously lower (P < 0.05). PRP combined with quadriceps training can accelerate cartilage repair of patients with KOA and reduce inflammatory factor levels and levels of MMPs, but the treatment effect of PRP depends on platelet concentration, with the best range of 1400–1800 × 10⁹/L. Too high or too low platelet concentrations will affect recovery of knee function.

Scaffold-free approaches for the fabrication of engineered articular cartilage tissue

Tissue engineered cartilaginous constructs have meet great advances in the past decades as a treatment for osteoarthritis, a degenerative disease affecting people all over the world as the population ages. Scaffold-free tissue engineered constructs are designed and developed in recent years with only cells and cell-derived matrix involved. Scaffold-free tissue constructs do not require cell adherence on exogenous materials and are superior to scaffold-based constructs in (1) relying on only cells to produce matrix, (2) not interfering cell-cell signaling, cell migration or small molecules diffusion after implantation and (3) introducing no exogenous impurities. In this review, three main scaffold-free methodologies for cartilage tissue engineering, the cell sheet technology, the phase transfer cell culture-living hyaline cartilage graft (PTCC-LhCG) system and the cell aggregate-based (bottom-up) methods, were reviewed, covering mold fabrication, decellularization and 3D bioprinting. The recent advances, medical applications, superiority and drawbacks were elaborated in detail.

Tubular Cardiac Tissue Bioengineered from Multi-Layered Cell Sheets for Use in the Treatment of Heart Failure

This chapter describes a method for creating tubular cardiac tissue in vitro. Thick cardiac tissue in a tubular configuration is prepared by stacking cell sheets stepwise on the inner wall of a segment of small intestine, which functions as a blood vessel bed. The capillaries of the small intestinal segment are fed by an artery and drained by a vein. Therefore, perfusion culture of the cardiac tissue is achieved by continuously infusing culture medium into the arterial vessel that supplies the segment of small intestine. The aim of this technique is to fabricate tubular cardiac tissue that can function as a pump by sequentially implanting and culturing cardiac cell sheets on the inner wall of a perfused segment of small intestine.

Light on osteoarthritic joint: from bench to bed

Osteoarthritis (OA) is one of the rapidly growing disability-associated conditions with population aging worldwide. There is a pressing need for precise diagnosis and timely intervention for OA in the early stage. Current clinical imaging modalities, including pain radiography, magnetic resonance imaging, ultrasound, and optical coherent tomography, are limited to provide structural changes when the damage has been established or advanced. It prompts further endeavors in search of novel functional and molecular imaging, which potentially enables early diagnosis and intervention of OA. A hybrid imaging modality based on photothermal effects, photoacoustic imaging, has drawn wide attention in recent years and has seen a variety of biomedical applications, due to its great performance in yielding high-contrast and high-resolution images from structure to function, from tissue down to molecular levels, from animals to human subjects. Photoacoustic imaging has witnessed gratifying potentials and preliminary effects in OA diagnosis. Regarding the treatment of OA, photothermal-triggered therapy has exhibited its attractions for enhanced therapeutic outcomes. In this narrative review, we will discuss photoacoustic imaging for the diagnosis and monitoring of OA at different stages. Structural, functional, and molecular parameter changes associated with OA joints captured by photoacoustics will be summarized, forming the diagnosis perspective of the review. Photothermal therapy applications related to OA will also be discussed herein. Lastly, relevant clinical applications and its potential solutions to extend photoacoustic imaging to deeper OA situations have been proposed. Although some aspects may not be covered, this mini review provides a better understanding of the diagnosis and treatment of OA with exciting innovations based on tissue photothermal effects. It may also inspire more explorations in the field towards earlier and better theranostics of OA.

The Developing Field of Scaffold-Free Tissue Engineering for Articular Cartilage Repair

Articular cartilage is critical for proper joint mobility as it provides a smooth and lubricated surface between articulating bones and allows for transmission of load to underlying bones. Extended wear or injury of this tissue can result in osteoarthritis, a degenerative disease affecting millions across the globe. Because of its low regenerative capacity, articular cartilage cannot heal on its own and effective treatments for injured joint restoration remain a challenge. Strategies in tissue engineering have been demonstrated as potential therapeutic approaches to regenerate and repair damaged articular cartilage. Although many of these strategies rely on the use of an exogenous three-dimensional scaffolds to regenerate cartilage, scaffold-free tissue engineering provides numerous advantages over scaffold-based methods. This review highlights the latest advancements in scaffold-free tissue engineering for cartilage and the potential for clinical translation.

Enhancing chondrogenic potential via mesenchymal stem cell sheet multilayering

Advanced tissue engineering approaches for direct articular cartilage replacement in vivo employ mesenchymal stem cell (MSC) sources, exploiting innate chondrogenic potential to fabricate hyaline-like constructs in vitro within three-dimensional (3D) culture conditions. Cell sheet technology represents one such advanced 3D scaffold-free cell culture platform, and previous work has shown that 3D MSC sheets are capable of in vitro hyaline-like chondrogenic differentiation. The present study aims to build upon this understanding and elucidate the effects of an established cell sheet manipulation technique, cell sheet multilayering, on fabrication of MSC-derived hyaline-like cartilage 3D layered constructs in vitro. To achieve this goal, multilayered MSC sheets are prepared and assessed for structural and biochemical transitions throughout chondrogenesis. Results support MSC multilayering as a means of increasing construct thickness and 3D cellular interactions related to in vitro chondrogenesis, including N-cadherin, connexin 43, and integrin β-1. Data indicate that increasing construct thickness from 14 μm (1-layer construct) to 25 μm (2-layer construct) increases these cellular interactions and subsequent in vitro MSC chondrogenesis. However, a clear initial thickness threshold (33 μm - 3-layer construct) is evident that decreases the rate and extent of in vitro chondrogenesis, specifically chondrogenic gene expressions (Sox9, aggrecan, type II collagen) and sulfated proteoglycan accumulation in deposited extracellular matrix (ECM). Together, these data support the utility of cell sheet multilayering as a platform for tailoring construct thickness and subsequent MSC chondrogenesis for future articular cartilage regeneration applications.

Cell sheet transplantation prevents inflammatory adhesions: A new treatment for adhesive otitis media

Introduction

We developed a new treatment method that combines tympanoplasty with transplantation of autologous cultured nasal mucosal epithelial cell sheets to regenerate the mucosa of patients with adhesive otitis media, which has been difficult to treat effectively. We verified whether this procedure could be performed safely and measured its therapeutic efficacy.

Methods

Autologous nasal mucosal epithelial cell sheets were manufactured at a good manufacturing practice-compliant cell processing facility using autologous nasal mucosal tissue. We performed tympanoplasty and transplanted the cell sheets into the middle ear cavity in six patients with adhesive otitis media.

Results

The manufactured autologous cultured epithelial cell sheets met the predetermined quality standards and were successfully transplanted safely in all cases. Computed tomography findings after cell sheet transplantation showed that aeration in the tympanic cavity was maintained or restored in five of the six patients (83.3%). Four of the six (66.7%) patients had postoperative air-bone gap within 20 dB, which is considered a postoperative success in tympanoplasty for chronic middle ear disease.

Conclusions

The results of this clinical study suggest that tympanoplasty with cell sheet transplantation can be used to treat adhesive otitis media by reliably preventing re-adhesion of the tympanic membrane.

Freezing of cell sheets using a 3D freezer produces high cell viability after thawing

In cell therapy, transplanting an appropriate number of cells to the target site is crucial. One way to achieve this is to transplant cell sheets. Transplantation of cell sheets has already been utilized for various diseases in clinical practice. However, reducing the cost of cell sheet utilization is essential so as to facilitate the spread of regenerative medicine. Several ways to reduce costs are available, one of which is the use of allogenic cells. Another alternative is the use of cell sheets, which necessitates the development of methods for freezing cell sheets. This is the first study to report the use of a 3D Freezer for freezing cells. 3D Freezers have been used in the field of food processing and technology for a long time. The 3D Freezer freezes objects using cold air at a uniform temperature from all directions. In this study, we analyzed the cooling speed of human fibroblast sheets in 11 cell preservation solutions using a 3D Freezer and a Program Freezer. The cooling speed was −2 °C per min in the 3D Freezer. Supercooling in 10 cell preservation solutions was lower in the 3D Freezer than in the Program Freezer. Cell viability after freeze–thaw of the cell sheets using 3D Freezer was more than 70% in five cell preservation solutions. The levels of hepatocyte growth factor and transforming growth factor-β1 were the same not only in the fibroblast sheets frozen using the five cell preservation solutions but also in the non-frozen fibroblast sheets. These results suggest that the 3D Freezer can freeze implantable cell sheets immediately after thawing.

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3D Freezer operates using cold air with uniform temperature directed at an object from all directions.

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3D Freezer was trialed for freezing 3D cell sheets for the first time.

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3D Freezer can generate high cell viability after freezing and thawing for cell therapy.

Adipose-Derived Stem Cell Sheets Improve Early Biomechanical Graft Strength in Rabbits After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Although various reconstruction techniques are available for anterior cruciate ligament (ACL) injuries, a long recovery time is required before patients return to sports activities, as the reconstructed ACL requires time to regain strength. To date, several studies have reported use of mesenchymal stem cells in orthopaedic surgery; however, no studies have used adipose-derived stem cell (ADSC) sheets in ACL reconstruction (ACLR).

HYPOTHESIS

ADSC sheet transplantation can improve biomechanical strength of the autograft used in ACLR.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 68 healthy Japanese white rabbits underwent unilateral ACLR with a semitendinosus tendon autograft after random enrollment into a control group (no sheet; n = 34) and a sheet group (ADSC sheet; n = 34). At 2, 4, 8, 16, and 24 weeks after surgery, rabbits in each group were sacrificed to evaluate tendon-bone healing using histological staining, micro-computed tomography, and biomechanical testing. At 24 weeks, scanning transmission electron microscopy of the graft midsubstance was performed.

RESULTS

The ultimate failure load for the control and sheet groups, respectively, was as follows: 17.2 ± 5.5 versus 37.3 ± 10.3 (P = .01) at 2 weeks, 28.6 ± 1.9 versus 47.4 ± 10.4 (P = .003) at 4 weeks, 53.0 ± 14.3 versus 48.1 ± 9.3 (P = .59) at 8 weeks, 66.2 ± 9.3 versus 95.2 ± 43.1 (P = .24) at 16 weeks, and 66.7 ± 27.3 versus 85.3 ± 29.5 (P = .39) at 24 weeks. The histological score was also significantly higher in the sheet group compared with the control group at early stages up to 8 weeks. On micro-computed tomography, relative to the control group, the bone tunnel area was significantly narrower in the sheet group at 4 weeks, and the bone volume/tissue volume of the tendon-bone interface was significantly greater at 24 weeks. Scanning transmission electron microscopy at 24 weeks indicated that the mean collagen fiber diameter in the midsubstance was significantly greater, as was the occupation ratio of collagen fibers per field of view, in the sheet group.

CONCLUSION

ADSC sheets improved biomechanical strength, prevented bone tunnel enlargement, and promoted tendon-bone interface healing and graft midsubstance healing in an in vivo rabbit model.

CLINICAL RELEVANCE

ADSC sheets may be useful for early tendon-bone healing and graft maturation in ACLR.

Thermally-modulated cell separation columns using a thermoresponsive block copolymer brush as a packing material for the purification of mesenchymal stem cells

Cell therapy using mesenchymal stem cells (MSCs) is used as effective regenerative treatment. Cell therapy requires effective cell separation without cell modification and cellular activity reduction. In this study, we developed a temperature-modulated mesenchymal stem cell separation column. A temperature-responsive cationic block copolymer, poly(N,N-dimethylaminopropylacrylamide)-b-poly(N-isopropylacrylamide)(PDMAPAAm-b-PNIPAAm) brush with various cationic copolymer compositions, was grafted onto silica beads via two-step atom transfer radical polymerization. Using the packed beads, the elution behavior of the MSCs was observed. At 37 °C, the MSCs were adsorbed onto the column via both hydrophobic and electrostatic interactions with the PNIPAAm and PDMAPAAm segments of the copolymer brush, respectively. By reducing the temperature to 4 °C, the adsorbed MSCs were eluted from the column by reducing the hydrophobic and electrostatic interactions attributed to the hydration and extension of the PNIPAAm segment of the block copolymer brush. From the temperature-modulated adsorption and elution behavior of MSCs, a suitable DMAPAAm composition of the block copolymer brush was determined. Using the column, a mixture of MSC and BM-CD34⁺ cells was separated by simply changing the column temperature. The column was used to purify the MSCs, with purities of 78.2%, via a temperature change from 37 °C to 4 °C. Additionally, the cellular activity of the MSCs was retained throughout the column separation step. Overall, the obtained results show that the developed column is useful for MSC separation without cell modification and cellular activity reduction.