Crosslinked Collagen-Hyaluronic Acid Scaffold Enhances Interleukin-10 Under Co-Culture of Macrophages And Adipose-Derived Stem Cells.

The skin, the human body's largest organ, possesses a protective barrier that renders it susceptible to various injuries, including burns. Following burn trauma, the inflammatory process triggers both innate and adaptive immune responses, leading to the polarization of macrophages into two distinct phenotypes: the pro-inflammatory M1 and the anti-inflammatory M2. This dual response sets the stage for wound healing and subsequent tissue regeneration. Contributing to this transition from M1 to M2 polarization are human adipose-derived stem cells (ASCs), which employ paracrine signaling and inflammation suppression to enhance the remodeling phase. ASCs, when combined with biocompatible polymers, can be integrated into functional scaffolds. This study introduces an 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide-crosslinked (EDC-crosslinked) collagen-hyaluronic acid (Col-HA) scaffold assembled with ASCs, designed as a natural biomaterial device to modulate macrophage behavior in vitro under co-culture conditions. This innovation aims to improve wound healing processes. The EDC-crosslinked Col-HA scaffold favored the release of anti-inflammatory cytokines by ASCs, which indicated the M2 prevalence. In tissue engineering, a critical objective lies in the development of functional biomaterials capable of guiding specific tissue responses, notably the control of inflammatory processes. Thus, this research not only presents original findings but also points toward a promising avenue within regenerative medicine.

Electrospun Membrane Based on Poly(L-co-D,L lactic acid) and Natural Rubber Containing Copaiba Oil Designed as a Dressing with Antimicrobial Properties.

Drug delivery systems of natural antimicrobial compounds, such as copaiba oil (CO), have become relevant in the scientific community due to the recent prevalence of the public health complications related to antibiotic resistance. Electrospun devices act as an efficient drug delivery system for these bioactive compounds, reducing systemic side effects and increasing the effectiveness of the treatment. In this way, the present study aimed to evaluate the synergistic and antimicrobial effect of the direct incorporation of different concentrations of CO in a poly(L-co-D,L lactic acid) and natural rubber (NR) electrospun membrane. It was observed that CO showed bacteriostatic and antibacterial effects against S. aureus in antibiogram assays. The prevention of biofilm formation was confirmed via scanning electron microscopy. The test with crystal violet demonstrated strong bacteria inhibition in membranes with 75% CO. A decrease in hydrophilicity, observed in the swelling test, presented that the addition of CO promotes a safe environment for the recovery of injured tissue while acting as an antimicrobial agent. In this way, the study showed strong bacteriostatic effects of the CO incorporation in combination with electrospun membranes, a suitable feature desired in wound dressings in order to promote a physical barrier with prophylactic antimicrobial properties to avoid infections during tissue healing.

Analysis of the biocompatibility of a biocelulose and a poly L- lactic acid membrane

The use of selective barriers as resorbable membranes has become a routine clinical procedure for guided bone regeneration. Therefore, the production of membranes with a low inflammatory potential during their resorption process has become the goal of a considerable number of researches. Aim: The purpose of the present study was to evaluate the biocompatibility of poly (L- lactic acid) (PLLA) and biocelulose membranes (BC) inserted in the subcutaneous tissue on the dorsum of rats. Methods: Fifteen animals underwent surgical procedures for the insertion of 4 types of membranes: COL (Collagen membrane) ­ Control Group; BC (Biocellulose membrane); BCAg (Biocellulose membrane impregnated with Silver); PLLA (Poly (L-lactic acid) membrane). All membrane types were inserted into each animal. Animals were euthanized after 3, 7, and 15 days of the surgical procedure. Descriptive histological analyses were carried out to investigate host tissue reaction to membrane presence by assessing the anti-inflammatory process composition associated with the membrane resorption and the presence of foreign-body reaction or encapsulation. Results: The BC membranes showed a higher degree of inflammation and poor pattern of integration with the surrounding tissues than the PLLA and COL membranes. Conclusion: The PLLA and COL membranes present better biocompatibility than the BC membranes

Poly (L-Lactic Acid) Cell-Laden Scaffolds Applied on Swine Model of Tracheal Fistula.

INTRODUCTION: Tracheal fistula (TF) treatments may involve temporary orthosis and further ablative procedures, which can lead to infection. Thus, TF requires other therapy alternatives development. The hypothesis of this work was to demonstrate the feasibility of a tissue-engineered alternative for small TF in a preclinical model. Also, its association with suture filaments enriched with adipose tissue-derived mesenchymal stromal stem cells (AT-MSCs) was assessed to determine whether it could optimize the regenerative process. METHODS: Poly (L-Lactic acid) (PLLA) membranes were manufactured by electrospinning and had morphology analyzed by scanning electron microscopy. AT-MSCs were cultured in these scaffolds and in vitro assays were performed (cytotoxicity, cellular adhesion, and viability). Subsequently, these cellular constructs were implanted in an animal small TF model. The association with suture filaments containing attached AT-MSCs was present in one animal group. After 30 d, animals were sacrificed and regenerative potential was evaluated, mainly related to the extracellular matrix remodeling, by performing histopathological (Hematoxylin-Eosin and trichrome Masson) and immunohistochemistry (Collagen I/II/III, matrix metalloproteinases-2, matrix metalloproteinases-9, vascular endothelial growth factor, and interleukin-10) analyses. RESULTS: PLLA membranes presented porous fibers, randomly oriented. In vitro assays results showed that AT-MSCs attached were viable and maintained an active metabolism. Swine implanted with AT-MSCs attached to membranes and suture filaments showed aligned collagen fibers and a better regenerative progress in 30 d. CONCLUSIONS: PLLA membranes with AT-MSCs attached were useful to the extracellular matrix restoration and have a high potential for small TF treatment. Also, their association with suture filaments enriched with AT-MSCs was advantageous.

Addition of Wollastonite Fibers to Calcium Phosphate Cement Increases Cell Viability and Stimulates Differentiation of Osteoblast-Like Cells.

Calcium phosphate cement (CPC) that is based on α-tricalcium phosphate (α-TCP) is considered desirable for bone tissue engineering because of its relatively rapid degradation properties. However, such cement is relatively weak, restricting its use to areas of low mechanical stress. Wollastonite fibers (WF) have been used to improve the mechanical strength of biomaterials. However, the biological properties of WF remain poorly understood. Here, we tested the response of osteoblast-like cells to being cultured on CPC reinforced with 5% of WF (CPC-WF). We found that both types of cement studied achieved an ion balance for calcium and phosphate after 3 days of immersion in culture medium and this allowed subsequent long-term cell culture. CPC-WF increased cell viability and stimulated cell differentiation, compared to nonreinforced CPC. We hypothesize that late silicon release by CPC-WF induces increased cell proliferation and differentiation. Based on our findings, we propose that CPC-WF is a promising material for bone tissue engineering applications.

Bioresorbable scaffold as a dermal substitute.

INTRODUCTION: Bioresorbable polymers are often used in medical procedures. Since they are biocompatible, this class of materials is a viable alternative for cases in which tissue regeneration is strongly compromised. Bioresorbable synthetic polymers may be used as membranes to support and guide cell growth through the process of tissue repair. OBJECTIVE: To assess the efficiency of a porous bioresorbable membrane Poly (L-co-DL lactic acid)-co-trimethylene carbonate, PL-co-DLA-co-TMC, as a dermal substitute associated with partial skin graft in rats. METHODS: A 1.5×1.5 cm defect was created on the backs of 40 Wistar rats. The rats were divided into a control group, in which the defects were filled with partial skin graft, and a treated group, in which a membrane associated with the graft was implemented. The animals were sacrificed 7 days or 60 days after the procedure and the results were evaluated by macroscopic and microscopic analysis. RESULTS: The polymer was biocompatible and allowed better regeneration of the dermis with less shrinkage, unlike what occurs in second intention healing. Compared to the control group, the treated group showed a thicker and wider dermis with the presence of skin appendages, suggesting partial graft integration and better healing. The skin graft acted as a biological protection of the wound. CONCLUSION: The study material was shown to act as a biocompatible dermal substitute and promoted less scarring of the dermis. Further studies should be conducted to improve the methodology of the surgical procedure.

In vivo evaluation of porous hydrogel pins to fill osteochondral defects in rabbits.

OBJECTIVE: This experimental study aimed to evaluate the biological performance of poly (l-co-D, l-lactic acid)-co-trimetilene carbonate/poly (vinyl alcohol) (PLDLA-co TMC/PVA), hydrogel scaffolds, as an implant in the filling (and not in the repair) of osteochondral defects in New Zealand rabbits, assessing the influence of the material in tissue protection in vivo. METHODS: Twelve rabbits were divided into groups of nine and 16 weeks. In each animal, an osteochondral defect was created in both medial femoral condyles. In one knee, a hydrogel scaffold was implanted (pin group) and in the other, the defect was maintained (control group). A histological analysis of the material was performed after euthanasia. RESULTS: The condyles of the pin group showed no inflammatory reaction and were surrounded by a fibrous capsule. The control group presented higher bone growth in the areas of the defect, but with disorganized articular cartilage, evident fibrosis, bone exposure, atrophy, and proliferation of synovial membrane. CONCLUSION: The hydrogel pins are promising in filling osteochondral defects, generally do not cause inflammatory reactions, and are not effective in the repair of osteochondral defects.

OBJETIVO: Trabalho experimental para avaliar o desempenho biológico de arcabouços de hidrogel poli (l-co-D, l ácido lático)-co-trimetileno carbonato/poli (álcool vinílico) (PLDLA-co-TMC/PVA) como implante no preenchimento, e não no reparo, de defeito osteocondral em coelhos Nova Zelândia e verificar a influência do material na proteção tecidual in vivo. MÉTODOS: Foram usados 12 coelhos divididos em grupos de nove e 16 semanas. Em cada animal foi criado um defeito osteocondral em ambos os côndilos femorais mediais, em um foi implantado um arcabouço de hidrogel (grupo pino) e no outro foi mantido o defeito (grupo controle). Após o sacrifício dos animais, foi feita análise histológica do material. RESULTADOS: Os côndilos do grupo pino não evidenciaram reação inflamatória e estavam rodeados por cápsula fibrosa. Já no grupo controle, uma maior proliferação óssea foi observada nas áreas do defeito, porém com cartilagem articular desorganizada, fibrose evidente, atrofia com exposição óssea e proliferação de membrana sinovial. CONCLUSÃO: Os pinos de hidrogel são promissores na função de preenchimento de defeitos osteocondrais, não ocasionam, de modo geral, reação inflamatória e não são eficazes no reparo de defeitos osteocondrais.

In vivo evaluation of porous hydrogel pins to fill osteochondral defects in rabbits / Avaliação do desempenho in vivo de pinos porosos de hidrogel para preenchimento de defeito osteocondral em coelhos

ABSTRACT OBJECTIVE: This experimental study aimed to evaluate the biological performance of poly (l-co-D, l-lactic acid)-co-trimetilene carbonate/poly (vinyl alcohol) (PLDLA-co TMC/PVA), hydrogel scaffolds, as an implant in the filling (and not in the repair) of osteochondral defects in New Zealand rabbits, assessing the influence of the material in tissue protection in vivo. METHODS: Twelve rabbits were divided into groups of nine and 16 weeks. In each animal, an osteochondral defect was created in both medial femoral condyles. In one knee, a hydrogel scaffold was implanted (pin group) and in the other, the defect was maintained (control group). A histological analysis of the material was performed after euthanasia. RESULTS: The condyles of the pin group showed no inflammatory reaction and were surrounded by a fibrous capsule. The control group presented higher bone growth in the areas of the defect, but with disorganized articular cartilage, evident fibrosis, bone exposure, atrophy, and proliferation of synovial membrane. CONCLUSION: The hydrogel pins are promising in filling osteochondral defects, generally do not cause inflammatory reactions, and are not effective in the repair of osteochondral defects.

RESUMO OBJETIVO: Trabalho experimental para avaliar o desempenho biológico de arcabouços de hidrogel poli (L-co-D, L ácido lático)-co-trimetileno carbonato/poli (álcool vinílico) (PLDLA-co-TMC/PVA) como implante no preenchimento, e não no reparo, de defeito osteocondral em coelhos Nova Zelândia e verificar a influência do material na proteção tecidual in vivo. MÉTODOS: Foram usados 12 coelhos divididos em grupos de nove e 16 semanas. Em cada animal foi criado um defeito osteocondral em ambos os côndilos femorais mediais, em um foi implantado um arcabouço de hidrogel (grupo pino) e no outro foi mantido o defeito (grupo controle). Após o sacrifício dos animais, foi feita análise histológica do material. RESULTADOS: Os côndilos do grupo pino não evidenciaram reação inflamatória e estavam rodeados por cápsula fibrosa. Já no grupo controle, uma maior proliferação óssea foi observada nas áreas do defeito, porém com cartilagem articular desorganizada, fibrose evidente, atrofia com exposição óssea e proliferação de membrana sinovial. CONCLUSÃO: Os pinos de hidrogel são promissores na função de preenchimento de defeitos osteocondrais, não ocasionam, de modo geral, reação inflamatória e não são eficazes no reparo de defeitos osteocondrais.

Poly(lactic-co-glycolic acid) matrix incorporated with nisin as a novel antimicrobial biomaterial.

The use of poly(lactic-co-glycolic acid) (PLGA) matrix as a biomolecule carrier has been receiving great attention due to its potential therapeutic application. In this context, we investigated the PLGA matrix capacity to incorporate nisin, an antimicrobial peptide capable of inhibiting the growth of Gram-positive bacteria and bacterial spores germination. Nisin-incorporated PLGA matrices were evaluated based on the inhibitory effect against the nisin-bioindicator Lactobacillus sakei. Additionally, the PLGA-nisin matrix stability over an 8-months period was investigated, as well as the nisin release profile. For the incorporation conditions, we observed that a 5 h incorporation time, at 30 °C, with 250 µg/mL nisin solution in PBS buffer pH 4.5, resulted in the highest inhibitory activity of 2.70 logAU/mL. The PLGA-nisin matrix was found to be relatively stable and showed sustained drug delivery, with continuous release of nisin for 2 weeks. Therefore, PLGA-nisin matrix is could be used as a novel antimicrobial delivery system and an alternative to antibiotics incorporated into PLGA matrices.

Synthesis, Characterization, and Osteoblastic Cell Culture of Poly(L-co-D,L-lactide-co-trimethylene carbonate) Scaffolds.

Lactide-based polymers have been widely investigated as materials for tissue engineering. However, characteristics such as low flexibility and elongation tend to limit particular applications, although these can be enhanced by adding plasticizers such as trimethylene carbonate (TMC) to the polymer chain of the copolymer poly(L-lactide-co-D,L-lactide) (PLDLA). The aim of this work was to synthesize and characterize a terpolymer of L-lactide, D,L-lactide, and TMC. The polymers were synthesized from 30% TMC by bulk polymerization and resulted in an average molar mass >10(5) g/mol. Thermal investigation of PLDLA-TMC showed a decrease in the glass transition and onset temperatures compared to PLDLA. PLDLA-TMC scaffolds stimulated the proliferation and normal phenotypic manifestations of cultured osteoblasts. These results show that it was possible to produce a terpolymer from L-lactide, D,L-lactide, and TMC. Scaffolds of this terpolymer had important characteristics that could be useful for applications in bone tissue engineering.

PLDLA/PCL-T Scaffold for Meniscus Tissue Engineering.

The inability of the avascular region of the meniscus to regenerate has led to the use of tissue engineering to treat meniscal injuries. The aim of this study was to evaluate the ability of fibrochondrocytes preseeded on PLDLA/PCL-T [poly(L-co-D,L-lactic acid)/poly(caprolactone-triol)] scaffolds to stimulate regeneration of the whole meniscus. Porous PLDLA/PCL-T (90/10) scaffolds were obtained by solvent casting and particulate leaching. Compressive modulus of 9.5±1.0 MPa and maximum stress of 4.7±0.9 MPa were evaluated. Fibrochondrocytes from rabbit menisci were isolated, seeded directly on the scaffolds, and cultured for 21 days. New Zealand rabbits underwent total meniscectomy, after which implants consisting of cell-free scaffolds or cell-seeded scaffolds were introduced into the medial knee meniscus; the negative control group consisted of rabbits that received no implant. Macroscopic and histological evaluations of the neomeniscus were performed 12 and 24 weeks after implantation. The polymer scaffold implants adapted well to surrounding tissues, without apparent rejection, infection, or chronic inflammatory response. Fibrocartilaginous tissue with mature collagen fibers was observed predominantly in implants with seeded scaffolds compared to cell-free implants after 24 weeks. Similar results were not observed in the control group. Articular cartilage was preserved in the polymeric implants and showed higher chondrocyte cell number than the control group. These findings show that the PLDLA/PCL-T 90/10 scaffold has potential for orthopedic applications since this material allowed the formation of fibrocartilaginous tissue, a structure of crucial importance for repairing injuries to joints, including replacement of the meniscus and the protection of articular cartilage from degeneration.

The use of vancomycin-loaded poly-l-lactic acid and poly-ethylene oxide microspheres for bone repair: an in vivo study.

OBJECTIVE: The aim of this study was to investigate bone repair after the implantation of vancomycin-loaded poly-L-lactic acid/poly-ethylene oxide microspheres compared with vancomycin-unloaded poly-L-lactic acid/poly-ethylene oxide microspheres. METHODS: Poly-L-lactic acid/poly-ethylene oxide microspheres were implanted in rat tibiae and evaluated for periods of 2, 4, 8, and 12 days and 4, 8, 16, and 32 weeks. The groups implanted with vancomycin-loaded and vancomycin-unloaded microspheres were compared. Histopathologic (semi-quantitative) and histomorphometric analyses were performed to evaluate the bone formation process. RESULTS: During the first period (second day), fibrin and hemorrhaging areas were observed to be replaced by granulation tissue around the microspheres. Woven bone formation with progressive maturation was observed. All of the histopathological findings, evaluated by a semi-quantitative assay and a quantitative analysis (percentage of bone formation), were similar between the two groups. CONCLUSION: Vancomycin-loaded poly-L-lactic acid/poly-ethylene oxide microspheres are a good bone substitute candidate for bone repair. Local antibiotic therapy using vancomycin-loaded poly-L-lactic acid/poly-ethylene oxide microspheres should be considered after the microbiological evaluation of its efficacy.

The use of vancomycin-loaded poly-l-lactic acid and poly-ethylene oxide microspheres for bone repair: an in vivo study

OBJECTIVE: The aim of this study was to investigate bone repair after the implantation of vancomycin-loaded poly-L-lactic acid/poly-ethylene oxide microspheres compared with vancomycin-unloaded poly-L-lactic acid/poly-ethylene oxide microspheres. METHODS: Poly-L-lactic acid/poly-ethylene oxide microspheres were implanted in rat tibiae and evaluated for periods of 2, 4, 8, and 12 days and 4, 8, 16, and 32 weeks. The groups implanted with vancomycin-loaded and vancomycin-unloaded microspheres were compared. Histopathologic (semi-quantitative) and histomorphometric analyses were performed to evaluate the bone formation process. RESULTS: During the first period (second day), fibrin and hemorrhaging areas were observed to be replaced by granulation tissue around the microspheres. Woven bone formation with progressive maturation was observed. All of the histopathological findings, evaluated by a semi-quantitative assay and a quantitative analysis (percentage of bone formation), were similar between the two groups. CONCLUSION: Vancomycin-loaded poly-L-lactic acid/poly-ethylene oxide microspheres are a good bone substitute candidate for bone repair. Local antibiotic therapy using vancomycin-loaded poly-L-lactic acid/poly-ethylene oxide microspheres should be considered after the microbiological evaluation of its efficacy.

Prótese meniscal de polímero bioabsorvível: estudo em coelhos / Bioresorbable polymeric meniscal prosthesis: study in rabbits

OBJETIVO: Obter o crescimento de um neomenisco por entre as porosidades da prótese com objetivo de proteger a cartilagem articular do joelho. MÉTODOS: Foram operados 70 joelhos de 35 coelhos Nova Zelândia com idades entre cinco e sete meses, pesando entre dois e 3,8 quilogramas, sendo 22 machos e 13 fêmeas. Submetidos no mesmo tempo cirúrgico à meniscectomia medial nos dois joelhos, em um lado foi implantada prótese meniscal de polímero bioabsorvível composta por 70 por cento de poli (dioxanona) e 30 por cento de poli (L-ácido láctico). Realizada eutanásia com diferentes tempos pós-implante. Os côndilos femorais mediais e o neomenisco foram submetidos à análise histológica, observando-se a degradação e absorção da prótese, o crescimento de tecido meniscal na mesma, e o grau de degradação da cartilagem articular dos côndilos femorais, medido pelo histograma. RESULTADOS: Os dados obtidos avaliaram o crescimento de tecido histologicamente semelhante ao menisco normal, com absorção gradual da prótese e a porcentagem de condrócitos no lado controle e no lado com implante da prótese. CONCLUSÕES: Ocorreu crescimento de tecido por entre os poros da prótese com características histológicas semelhantes a do menisco normal de coelho. A cartilagem articular dos côndilos femorais no lado com implante da prótese apresenta maior número de condrócitos em todas as suas camadas.

OBJECTIVE: To induce the ingrowth of a neomeniscus between the pores of the prosthesis in order to protect the articular cartilage of the knee. METHODS: 70 knees of 35 New Zealand rabbits were operated. The rabbits were five to seven months old, weighed 2 to 3.8 kilograms. 22 were male and 13 were female. Each animal underwent medial meniscectomy in both knees during the same time of surgery, having a bioresorbable polymeric meniscal prosthesis composed of 70 percent polydioxanone and 30 percent L-lactic acid polymer implanted in one side. They were submitted to euthanasia after different post-operative time points. The femoral condyles and the neomeniscus were submitted to histological analysis. Histogram was employed to analyze tissue ingrowth into the prosthesis, degradation and absorption of the prosthesis and tissue ingrowth and degradation of the femoral condyle cartilage. RESULTS: The data obtained evaluated the ingrowth of tissue histologically resembling a normal meniscus, with gradual prosthesis absorption and the percentage of chondrocytes on the control side and prosthesis side. CONCLUSION: Tissue ingrowth into the porous prosthesis histologically resembling a normal rabbit meniscus was observed. The articular cartilage of the femoral condyles on the prosthesis side presented more chondrocytes in all its layers.

Thermal, morphologic and mechanical characterization of poly (L-lactic acid)/poly (hydroxybutyrate-cohydroxyvalerate) blends

O desenvolvimento de polímeros bioabsorvíveis pode ser considerado como um avanço no desenvolvimento de materiais biomédicos. Materiais bioabsorvíveis apresentam numerosas aplicações na Medicina. A proposta deste trabalho foi estudar blendas de Poli(L-ácido láctico) e Poli(3-hidroxibutirato-co-3-hidroxivalerato) PLLA/PHBV em diferentes composições (100/0, 60/40, 50/50, 40/60, e 0/100), obtidas através da fusão dos polímeros em uma mini injetora Mini Max Molder, obtendo pinos de 31x90 mm. As blendas foram caracterizadas através das análises de Calorimetria Diferencial de Varredura(DSC), Análise Dinâmico-Mecânica(DMA), Microscopia Eletrônica de Varredura(SEM) e ensaios mecânicos. As análises de DSC e DMA mostraram que as blendas de PLLA/PHBV apresentaram duas temperaturas de transição vítrea, cristalização e fusão distintas, respectivas aos polímeros puros, indicando a imiscibilidade das blendas em todas as composições. Através do SEM foi possível observar que tanto os polímeros puros como as blendas apresentaram uma morfologia densa, sendo que nas blendas verificou-se a presença de duas fases, confirmando os dados de DSC e DMA. Os testes de ensaio mecânico de flexão mostraram que o PLLA impõe maior resistência mecânica e flexibilidade ao sistema. Devido à sua boa compatibilização térmica e mecânica, as blendas de PLLA/PHBV, mostraram ser uma boa alternativa para aplicação na área ortopédica