Dermo-epidermal organotypic cultures for in vitro evaluation of skin irritation and corrosion.

In recent years, in-vitro skin models for chemical hazard identification have been developed. Most of them consist only of human keratinocytes, neglecting the contribution of other skin constituents. Cultures containing the dermal and epidermal component provide an attractive system to investigate, in a more realistic model, toxicological responses, which represents a distinct advantage over keratinocytes-based models that do not mimic faithfully the in vivo environment. This study aimed to validate dermo-epidermal organotypic cultures (ORGs) as a platform to perform irritation and corrosion tests. Skin models were constructed by seeding keratinocytes on fibroblast-containing fibrin gels. After 21 days, the ORGs were evaluated histologically, and the irritant and corrosion potential was determined by means of viability measurements (MTT assay) and cytokine release, according to 431 and 439 OECD tests guidelines. Skin models showed similar histological characteristics to native skin and were able to classify different substances with high accuracy, showing their applicability to skin irritation and corrosion tests. Although cytokines release seems to be chemical-dependent, a tendency was observed, leading to the improvement of the prediction capacity. Nevertheless, further studies should be done to reduce variability in order to increase prediction capacity.

Arcabouço de PRP-gel associado a células tronco mesenquimais: uso em lesões condrais em modelo experimental equino / PRP-gel scaffold associated with mesenchymal stem cells: use in experimental chondral defect of equine models

O plasma rico em plaquetas (PRP) é conhecido por apresentar propriedades anabólicas, anti-inflamatórias e capacidade de gelificação. Atualmente o PRP é considerado eficaz na reparação da cartilagem, sendo sua capacidade de formação de gel indicada para o preenchimento de defeitos condrais. O objetivo desse estudo foi analisar o uso do PRP ativado, no formato de arcabouço, como suporte para o implante de células tronco mesenquimais (CTM), no preenchimento e tratamento de lesões condrais induzidas em equinos. Doze equinos foram submetidos a uma cirurgia artroscópica no tempo zero do experimento (T0), onde foi induzida uma lesão condral de 15 mm de diâmetro na tróclea medial femoral dos membros pélvicos direito. As 12 articulações foram divididas em dois grupos distintos com seis articulações cada (GA e GB). As articulações do GA foram submetidas ao tratamento com o implante de CTM em gel de PRP. As articulações de GB foram o grupo controle do experimento. As CTMs foram extraídas do tecido adiposo e o PRP em gel foi obtido por protocolo de dupla centrifugação seguido da adição de trombina liofilizada. Após cinco meses (T150) foi realizada nova artroscopia para avaliação macroscópica do local, coleta de amostras do tecido de reparação para análises de microscopia eletrônica, sendo realizadas imagens ressonância magnética e tomografia computadorizada no local do implante no GA. Observamos que o gel de PRP associado às CTM demonstrou ser adequado no tratamento de defeitos condrais experimentais dos equinos. GA evidenciou um melhor aspecto macroscópico e microscópico do tecido de reparação, sendo que GB mostrou maior desorganização das fibras colágenas. Nas imagens de ressonância magnética e tomografia computadorizada apenas foi relevante o local da lesão condral. O arcabouço de gel de PRP demonstrou ser apropriado no suporte do tratamento com as CTMs, sendo de fácil aplicação e efetivo, demonstrando resultados promissores na reparação de lesões condrais induzidas.(AU)

The platelet-rich plasma (PRP) is characterized by its anabolic, anti-inflammatory and gelling capability. Nowadays, the PRP is considered effective in the repair of cartilage defects, and its gelling capability is proper to filling chondral defects. So, the aim of this study was to investigate the use of activated PRP as a fibrin gel scaffold, such as support for the use with mesenchymal stem cells (MSC), on the treatment of experimentally chondral articular defects. Twelve horses were subjected to an arthroscopic surgery at time zero of the experiment (T0). A chondral defect of 15 mm diameter was created on the medial femoral trochlea and these 12 joints were divided into two groups each with six joints in each group (GA and GB). The joints of the GA were treated with implantation of MSC and PRP-gel. GB joints were the control group. MSCs were cultivated from adipose tissue and PRP-gel was obtained by double centrifugation protocol followed by addition of lyophilized thrombin. After five months (T150) was performed new arthroscopy for macroscopic evaluation of the defect local, collect samples of tissue repair for electron microscopy assessment and also was implemented a magnetic resonance images and computed tomography on GA. It was observed that the PRP-gel associated with CTMs showed a suitable treatment of experimental chondral defects in horses. GA showed a better macroscopic and microscopic appearance of the tissue repair. GB showed smaller number of chondrocytes and increased collagen fibers disorganization. At the magnetic resonance and computed tomography imaging only the local of chondral defect was viewed. The PRP-gel scaffold was satisfactory to use and support MSCs implantation. It showed an easy handling and it was effective, showing a promising results in the repair of induced chondral defects.(AU)

Arcabouço de PRP-gel associado a células tronco mesenquimais: uso em lesões condrais em modelo experimental equino / PRP-gel scaffold associated with mesenchymal stem cells: use in experimental chondral defect of equine models

O plasma rico em plaquetas (PRP) é conhecido por apresentar propriedades anabólicas, anti-inflamatórias e capacidade de gelificação. Atualmente o PRP é considerado eficaz na reparação da cartilagem, sendo sua capacidade de formação de gel indicada para o preenchimento de defeitos condrais. O objetivo desse estudo foi analisar o uso do PRP ativado, no formato de arcabouço, como suporte para o implante de células tronco mesenquimais (CTM), no preenchimento e tratamento de lesões condrais induzidas em equinos. Doze equinos foram submetidos a uma cirurgia artroscópica no tempo zero do experimento (T0), onde foi induzida uma lesão condral de 15 mm de diâmetro na tróclea medial femoral dos membros pélvicos direito. As 12 articulações foram divididas em dois grupos distintos com seis articulações cada (GA e GB). As articulações do GA foram submetidas ao tratamento com o implante de CTM em gel de PRP. As articulações de GB foram o grupo controle do experimento. As CTMs foram extraídas do tecido adiposo e o PRP em gel foi obtido por protocolo de dupla centrifugação seguido da adição de trombina liofilizada. Após cinco meses (T150) foi realizada nova artroscopia para avaliação macroscópica do local, coleta de amostras do tecido de reparação para análises de microscopia eletrônica, sendo realizadas imagens ressonância magnética e tomografia computadorizada no local do implante no GA. Observamos que o gel de PRP associado às CTM demonstrou ser adequado no tratamento de defeitos condrais experimentais dos equinos. GA evidenciou um melhor aspecto macroscópico e microscópico do tecido de reparação, sendo que GB mostrou maior desorganização das fibras colágenas. Nas imagens de ressonância magnética e tomografia computadorizada apenas foi relevante o local da lesão condral. O arcabouço de gel de PRP demonstrou ser apropriado no suporte do tratamento com as CTMs, sendo de fácil aplicação e efetivo, demonstrando resultados promissores na reparação de lesões condrais induzidas.(AU)

The platelet-rich plasma (PRP) is characterized by its anabolic, anti-inflammatory and gelling capability. Nowadays, the PRP is considered effective in the repair of cartilage defects, and its gelling capability is proper to filling chondral defects. So, the aim of this study was to investigate the use of activated PRP as a fibrin gel scaffold, such as support for the use with mesenchymal stem cells (MSC), on the treatment of experimentally chondral articular defects. Twelve horses were subjected to an arthroscopic surgery at time zero of the experiment (T0). A chondral defect of 15 mm diameter was created on the medial femoral trochlea and these 12 joints were divided into two groups each with six joints in each group (GA and GB). The joints of the GA were treated with implantation of MSC and PRP-gel. GB joints were the control group. MSCs were cultivated from adipose tissue and PRP-gel was obtained by double centrifugation protocol followed by addition of lyophilized thrombin. After five months (T150) was performed new arthroscopy for macroscopic evaluation of the defect local, collect samples of tissue repair for electron microscopy assessment and also was implemented a magnetic resonance images and computed tomography on GA. It was observed that the PRP-gel associated with CTMs showed a suitable treatment of experimental chondral defects in horses. GA showed a better macroscopic and microscopic appearance of the tissue repair. GB showed smaller number of chondrocytes and increased collagen fibers disorganization. At the magnetic resonance and computed tomography imaging only the local of chondral defect was viewed. The PRP-gel scaffold was satisfactory to use and support MSCs implantation. It showed an easy handling and it was effective, showing a promising results in the repair of induced chondral defects.(AU)

A new heterologous fibrin sealant as a scaffold to cartilage repair-Experimental study and preliminary results.

Autologous fibrin gel is commonly used as a scaffold for filling defects in articular cartilage. This biomaterial can also be used as a sealant to control small hemorrhages and is especially helpful in situations where tissue reparation capacity is limited. In particular, fibrin can act as a scaffold for various cell types because it can accommodate cell migration, differentiation, and proliferation. Despite knowledge of the advantages of this biomaterial and mastery of the techniques required for its application, the durability of several types of sealant at the site of injury remains questionable. Due to the importance of such data for evaluating the quality and efficiency of fibrin gel formulations on its use as a scaffold, this study sought to analyze the heterologous fibrin sealant developed from the venom of Crotalus durissus terrificus using studies in ovine experimental models. The fibrin gel developed from the venom of this snake was shown to act as a safe, stable, and durable scaffold for up to seven days, without causing adverse side effects. Fibrin gel produced from the venom of the Crotalus durissus terrificus snake possesses many clinical and surgical uses. It presents the potential to be used as a biomaterial to help repair skin lesions or control bleeding, and it may also be used as a scaffold when applied together with various cell types. The intralesional use of the fibrin gel from the venom of this snake may improve surgical and clinical treatments in addition to being inexpensive and adequately consistent, durable, and stable. The new heterologous fibrin sealant is a scaffold candidate to cartilage repair in this study.