Minipig Model Research Articles

Pharmacokinetics and pharmacodynamics of standard nerve agent medical countermeasures in Göttingen Minipigs

Animal research continues to serve a critical role in the testing and development of medical countermeasures. The Göttingen minipig, developed for laboratory research, may provide many benefits for addressing research questions within chemical defense. Targeted development of the Göttingen minipig model could reduce reliance upon non-human primates, and improve study design, statistical power, and throughput to advance medical countermeasures for regulatory approval and fielding. In this vein, we completed foundational pharmacokinetics and physiological safety studies of intramuscularly administered atropine sulfate, pralidoxime chloride (2-PAM), and diazepam across a broad range of doses (1–6 autoinjector equivalent) using adult male Göttingen minipigs (n=11; n=4–8/study) surgically implanted with vascular access ports and telemetric devices to monitor cardiovascular, respiratory, arterial pressure, and temperature signals. Pharmacokinetic data were orderly and the concentration maximum mirrored available human data at comparably scaled doses clearly for atropine, moderately for 2-PAM, and poorly for diazepam. Time to peak concentration approximated 2, 7, and 20 min for atropine, 2-PAM, and diazepam, respectively, and the elimination half-life of these drugs approximated 2 hr (atropine), 3 hr (2-PAM), and 8 hr (diazepam). Atropine sulfate dose-dependently increased the magnitude and duration of tachycardia and decreased the PR and ST intervals (consistent with findings obtained from other species). Mild hypothermia was observed at the highest diazepam dose. Göttingen minipigs appear to provide a ready and appropriate large animal alternative to non-human primates, and further development and evaluation of novel nerve agent medical countermeasures and treatment strategies in this model are justified.

Self-crossing hyaluronic acid filler with combination use of polydioxanone thread in minipig model.

The advances of self-crossing hyaluronic acid (SC-HA) fillers combination use with polydioxanone thread in minipigs were examined for compatibility, effectiveness, and immune response. A 12-week experiment was conducted using 6 minipigs (3 male and 3 female each) to evaluate the effects of SC-HA filler. The molecular weight of SC-HA filler was fixed at 200 kDa and alternative storage modulus of G80, G250, and G500 were examined. The procedure involved injecting SC-HA filler and polydioxanone threads into the skin tissue of anesthetized minipigs, and tissue sampling after 1 month (three minipigs), and 3 months (three minipigs) for histological staining and analysis. The immune reaction was observed during the experiment. The practitioner reported it was easy to inject the SC-HA filler in combination with polydioxanone threads. All four storage modulus of SC-HA fillers were injectable within the polydioxanone thread containing cannula. Also, during the procedure, there were no immune responses at the treated sites. The results of the histological tissue examination confirmed that there was no chemical interaction between SC-HA filler and the existing polydioxanone thread, and it was observed that SC-HA filler was more uniformly distributed within the tissue with lower storage modulus, resulting in a higher production of collagen in the surrounding filler. When combined with scaffold polydioxanone thread, the scaffold polydioxanone thread helped spread the filler evenly, resulting in a more evenly distributed collagen around the filler. Today, the combination therapy of filler and polydioxanone thread in one procedure is challenging due to the high viscosity of conventional fillers. However, this study confirmed that combination therapy of filler and polydioxanone thread is possible with SC-HA fillers. Additionally, it was found that polydioxanone thread does not seem to interfere with the crosslinking reaction of SC-HA filler, and if used with a higher pH of polydioxanone, it may enhance the cross-linking reaction and achieve a higher viscosity value. Finally, the study resulted in the idea of concrete as SC-HA filler and reinforcing rod for polydioxanone thread.

Ferroptosis, Inflammation, and Microbiome Alterations in the Intestine in the Göttingen Minipig Model of Hematopoietic-Acute Radiation Syndrome.

Hematopoietic acute radiation syndrome (H-ARS) involves injury to multiple organ systems following total body irradiation (TBI). Our laboratory demonstrated that captopril, an angiotensin-converting enzyme inhibitor, mitigates H-ARS in Göttingen minipigs, with improved survival and hematopoietic recovery, as well as the suppression of acute inflammation. However, the effects of captopril on the gastrointestinal (GI) system after TBI are not well known. We used a Göttingen minipig H-ARS model to investigate captopril's effects on the GI following TBI (60Co 1.79 or 1.80 Gy, 0.42-0.48 Gy/min), with endpoints at 6 or 35 days. The vehicle or captopril (0.96 mg/kg) was administered orally twice daily for 12 days, starting 4 h post-irradiation. Ilea were harvested for histological, protein, and RNA analyses. TBI increased congestion and mucosa erosion and hemorrhage, which were modulated by captopril. GPX-4 and SLC7A11 were downregulated post-irradiation, consistent with ferroptosis at 6 and 35 days post-irradiation in all groups. Interestingly, p21/waf1 increased at 6 days in vehicle-treated but not captopril-treated animals. An RT-qPCR analysis showed that radiation increased the gene expression of inflammatory cytokines IL1B, TNFA, CCL2, IL18, and CXCL8, and the inflammasome component NLRP3. Captopril suppressed radiation-induced IL1B and TNFA. Rectal microbiome analysis showed that 1 day of captopril treatment with radiation decreased overall diversity, with increased Proteobacteria phyla and Escherichia genera. By 6 days, captopril increased the relative abundance of Enterococcus, previously associated with improved H-ARS survival in mice. Our data suggest that captopril mitigates senescence, some inflammation, and microbiome alterations, but not ferroptosis markers in the intestine following TBI.

133 Early Assessment of Burn Depth in a Yucatan Minipig Model Using Resonance Raman Spectroscopy

133 Early Assessment of Burn Depth in a Yucatan Minipig Model Using Resonance Raman Spectroscopy

Sustained Release of Salicylic Acid for Halting Peri-Implantitis Progression in Healthy and Hyperglycemic Systemic Conditions: A Gottingen Minipig Model.

To develop a peri-implantitis model in a Gottingen minipig and evaluate the effect of local application of salicylic acid poly(anhydride-ester) (SAPAE) on peri-implantitis progression in healthy, metabolic syndrome (MS), and type-2 diabetes mellitus (T2DM) subjects. Eighteen animals were allocated to three groups: (i) control, (ii) MS (diet for obesity induction), and (iii) T2DM (diet plus streptozotocin for T2DM induction). Maxillary and mandible premolars and first molar were extracted. After 3 months of healing, four implants per side were placed in both jaws of each animal. After 2 months, peri-implantitis was induced by plaque formation using silk ligatures. SAPAE polymer was mixed with mineral oil (3.75 mg/μL) and topically applied biweekly for up to 60 days to halt peri-implantitis progression. Periodontal probing was used to assess pocket depth over time, followed by histomorphologic analysis of harvested samples. The adopted protocol resulted in the onset of peri-implantitis, with healthy minipigs taking twice as long to reach the same level of probing depth relative to MS and T2DM subjects (∼3.0 mm), irrespective of jaw. In a qualitative analysis, SAPAE therapy revealed decreased levels of inflammation in the normoglycemic, MS, and T2DM groups. SAPAE application around implants significantly reduced the progression of peri-implantitis after ∼15 days of therapy, with ∼30% lower probing depth for all systemic conditions and similar rates of probing depth increase per week between the control and SAPAE groups. MS and T2DM conditions presented a faster progression of the peri-implant pocket depth. SAPAE treatment reduced peri-implantitis progression in healthy, MS, and T2DM groups.

Liquid respiratory desaturation. The first experience of application on large biological objects

Introduction. This article is a continuation of the publication of the experimental studies results of prevention of acute decompression sickness (aDCS) in laboratory animals by the method of liquid respiratory desaturation (LRDS). LRDS is a method of preventing decompression disorders by the excretion of metabolically indifferent gases (in particular nitrogen) from the body during spontaneous respiration with liquid or artificial liquid lung ventilation (ALLV), by dissolved gas concentration gradient "from tissues to respiratory fluid". The method allows to provide rapid desaturation of the body from metabolically indifferent gases in the process of liquid respiration before and/or during decompression, thereby creating conditions for application of ultra-fast decompression profiles without the risk of decompression disorders.
 The aim of the study was to confirm the possibility of LRDS being a method of DCS prevention on large laboratory animals (minipigs).
 Materials and methods. The studies were performed on Wiessenau minipigs (n=8) — male and female, aged 4–5.5 months and weighing 7.1–11.2 kg. Animals of the control (n=4) and experimental (n=4) groups were subjected by compression by keeping in an air environment under high pressure (absolute 0.5 MPa for 60 minutes) to saturate tissues with indifferent gas (nitrogen). After compression experimental group was exposed to 30-minute ALLV with a liquid (perfluorodecalin) saturated with an oxygen under normobaric conditions. Air environment pressure during procedure of artificial lung ventilation was kept at 0.5 MPa. Decompression of the control and experimental groups was carried out in non-stop manner for 80 and 40 seconds respectively. The investigation of severity of clinical manifestations of DCS (changes in hemodynamic and respiratory parameters) including ultrasonic examination of gas bubbles in the heart and large vessels of the liver and as well as survival of animals in groups and pathoanatomical changes was performed.
 Results of the study. Clinical manifestations, ultrasonic scanning of the heart and venous vessels of the liver, as well as morphological examination data indicated the development of severe acute post-decompression disorders (PDD) in animals of the control group, which caused deaths in 100% of cases. Meanwhile all animals in experimental group survived and their state was stable. According to ultrasonic examination, the presence of small number of gas bubbles in the right-side heart chambers and liver's venous vessels being noted, but they disappeared after several hours. Deviations of the respiration's parameters function from background values (shortness of breath of a mixed type with the participation of auxiliary muscles, etc.) observed from the 2nd to the 4th day after ALLV, as well as compensatory reactions from the cardiovascular system (heart rate variability and instability of hemodynamic parameters) were caused by ALLV.
 Conclusions. Compressed air exposure 0.5 MPa for 60 minutes followed by 80 seconds of non-stop decompression allows to provoke the severe acute PDD minipigs model, manifested by pronounced intravascular gas formation, the development of acute respiratory and cardiovascular insufficiency causing the development of adverse outcomes.
 The ultrasound method of visual assessment of intravascular gas formation severity, adapted for minipigs, together with the dynamics of changes in the indicators of respiratory and cardiovascular systems makes possible to assess not only state of animal under anesthesia, but also the effectiveness of PDD prevention measures.
 The usage of ALLV with PFC liquid completely saturated with 100% oxygen under normobaric conditions makes possible partial removal of indifferent gas (nitrogen) dissolved in tissues of experimental animals during exposition in a compressed air environment before decompression and thereby carry out the prevention of DCS by LRDS method. It makes possible to implement successfully ultra-fast decompression profiles, incompatible with life in the control group.
 The state of animals from experimental group after LRDS is characterized by lung impairment caused by ALLV in hyperbaric conditions accompanied by temporary changes of external respiration function and compensatory reactions of cardiovascular system, observed during first 4 days.
 Ethics. The study was conducted in accordance with the ethical principles of the Declaration of Helsinki. The Clinical Study Protocol was approved by local Ethics Committee of The Federal State Budgetary Scientific Institution «Izmerov Research Institute of Occupational Health».

The Goettingen minipig as an experimental model in wound-healing studies

BackgroundDeep dermal wounds in extensive burns and chronic wound-healing disorders represent a significant medical problem and require a high level of therapy to reduce the risk of infection and other long-term consequences, such as amputation. A better understanding of the wound-healing processes is essential, and animal models are indispensable to fundamental research. ObjectiveThis study aimed to provide a transparent protocol and prove the effectiveness of an in vivo porcine model using Goettingen minipigs for wound-healing studies. Material and methodsThirteen female Goettingen minipigs were kept in species-appropriate housing and were treated according to the German law for the protection of animals. The study was performed with permission from the local ethical review committee of animal welfare. The experimental procedure for studying dermal regeneration in 102 full-thickness wounds through clinical observation and histological analysis, focusing on neodermal formation, is described in detail. ResultsThe Goettingen minipig model proved to be suitable in wound-healing studies. The dermal regeneration was evident and viewable without wound contamination or any rejection reaction. The histological evaluations were also reliable and clearly presented the optimized wound healing of deep dermal wounds using the different therapeutic approaches. ConclusionGiven the great clinical need for alternative or complementary therapies, we considered the Goettingen minipig trial a reliable, ethically justifiable, effective, and reproducible in vivo model for wound-healing studies.

Performance of ATT and UDFF in the diagnosis of non-alcoholic fatty liver: An animal experiment

ObjectiveTo establish a Bama minipigs model with Non-Alcoholic Fatty Liver (NAFL) induced by a high-fat diet and investigate the application of attenuation coefficient (ATT) and ultrasound-derived fat fraction (UDFF) in the diagnosis of NAFL. MethodsSix-month-old male Bama minipigs were randomly divided into normal control and high-fat groups (n = 3 pigs per group), and fed with a control diet and high-fat diet for 32 weeks. Weight and body length were measured every four weeks, followed by quantitative ultrasound imaging (ATT and UDFF), blood biochemical markers, and liver biopsies on the same day. Using the Non-Alcoholic Fatty Liver Disease (NAFLD) Activity Score (NAS) as a reference, we analyzed the correlation between ATT, UDFF, and their score results. ResultsCompared with the normal control group, the body weight, body mass index (BMI), and serum levels of triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) in the High-fat group were significantly different at Week 12 (P < 0.05). Spearman correlation analysis showed that the ATT value was significantly correlated with NAS score (r = 0.76, P < 0.001), and the UDFF value was significantly correlated with NAS score (r = 0.80, P < 0.001). The optimal cut-off value of ATT and UDFF were 0.59 dB/cm/MHz and 5.5%, respectively. These values are optimal for diagnosis of NAFL in Bama minipig model. ConclusionATT and UDFF have a high correlation with steatosis, and can be used as a non-invasive method for early screening of hepatic steatosis, which can dynamically monitor the change of disease course.

High fat diet is associated with gut microbiota dysbiosis and decreased gut microbial derived metabolites related to metabolic health in young Göttingen Minipigs.

The objectives were 1) to characterize a Göttingen Minipig model of metabolic syndrome regarding its colon microbiota and circulating microbial products, and 2) to assess whether ovariectomized female and castrated male minipigs show similar phenotypes. Twenty-four nine-week-old Göttingen Minipigs were allocated to four groups based on sex and diet: ovariectomized females and castrated males fed either chow or high-fat diet (HFD) for 12 weeks. At study end, body composition and plasma biomarkers were measured, and a mixed meal tolerance test (MMT) and an intravenous glucose tolerance test (IVGTT) were performed. The HFD groups had significantly higher weight gain, fat percentage, fasting plasma insulin and glucagon compared to the chow groups. Homeostatic model assessment of insulin resistance index (HOMA-IR) was increased and glucose effectiveness derived from the IVGTT and Matsuda´s insulin sensitivity index from the MMT were decreased in the HFD groups. The HFD groups displayed dyslipidemia, with significantly increased total-, LDL- and HDL-cholesterol, and decreased HDL/non-HDL cholesterol ratio. The colon microbiota of HFD minipigs clearly differed from the lean controls (GuniFrac distance matrix). The main bacteria families driving this separation were Clostridiaceae, Fibrobacteraceae, Flavobacteriaceae and Porphyromonadaceae. Moreover, the species richness was significantly decreased by HFD. In addition, HFD decreased the circulating level of short chain fatty acids and beneficial microbial metabolites hippuric acid, xanthine and trigonelline, while increasing the level of branched chain amino acids. Six and nine metabolically relevant genes were differentially expressed between chow-fed and HFD-fed animals in liver and omental adipose tissue, respectively. The HFD-fed pigs presented with metabolic syndrome, gut microbial dysbiosis and a marked decrease in healthy gut microbial products and thus displayed marked parallels to human obesity and insulin resistance. HFD-fed Göttingen Minipig therefore represents a relevant animal model for studying host-microbiota interactions. No significant differences between the castrated and ovariectomized minipigs were observed.

Assessing the efficacy of a 100 ps Nd:YAG laser for tattoo removal in a minipig model.

Using a minipig model, we evaluated the efficacy of the 100 ps Nd:YAG laser in the removal of tattoo pigments, specifically blue, green, red, and yellow. We observed distinct pigment responses to 532/1064 nm wavelengths at various energy settings. Through a combination of clinical, spectroscopic, and histological methods, we found the 532 nm wavelength to be most effective in disrupting all colors, with notable results for green and yellow at 0.4 J/cm2 and red at 0.72 J/cm2. The 1064 nm wavelength reduced pigment in yellow (1.51 J/cm2), green (1.35 J/cm2), and blue (1.11 J/cm2) tattoos, but was surpassed by the 532 nm in efficiency. Our data underscores the crucial interplay between pigment traits and laser settings in tattoo removal. We advocate for tailored treatment strategies, integrating pigment hue and laser wavelength, to enhance removal outcomes.

Orthotopic forelimb transplantation in a Yucatan minipig model: Anatomic and in vivo study.

Above elbow transplants represent 19% of the upper extremity transplants. Previous large-animal models have been too distal or heterotopic, did not use immunosuppression and had short survival. We hypothesize that an orthotopic forelimb transplant model, under standard immunosuppression, is feasible and can be used to address questions on peri-transplant ischemia reperfusion injury, and post-transplantation vascular, immunologic, infectious, and functional outcomes. Four forelimbs were used for anatomical studies. Four mock transplants were performed to establish technique/level of muscle/tendon repairs. Four donor and four recipient female Yucatan minipigs were utilized for in-vivo transplants (endpoint 90-days). Forelimbs were amputated at the midarm and preserved through ex vivo normothermic perfusion (EVNP) utilizing an RBC-based perfusate. Hourly perfusate fluid-dynamics, gases, electrolytes were recorded. Contractility during EVNLP was graded hourly using the Medical Research Council scale. EVNP termination criteria included systolic arterial pressure ≥115 mmHg, compartment pressure ≥30 mmHg (at EVNP endpoint), oxygen saturation reduction of 20%, and weight change ≥2%. Indocyanine green (ICG) angiography was performed after revascularization. Limb rejection was evaluated clinically (rash, edema, temperature), and histologically (BANFF classification) collecting per cause and protocol biopsies (POD 1, 7, 30, 60 and endpoint). Systemic infections were assessed by blood culture and tissue histology. CT scan was used to confirm bone bridging at endpoint. Animals 2, 4 reached endpoint with grade 0-I rejection. Limbs 1, 3 presented grade III rejection on days 6, 61. CsA troughs averaged 461 ± 189 ng/mL. EVNLP averaged 4.3 ± 0.52 h. Perfusate lactate, PO2 , and pH were 5.6 ± 0.9 mmol/L, 557 ± 72 mmHg and 7.5 ± 0.1, respectively. Muscle contractions were 4 [1] during EVNLP. Transplants 2, 3, 4 showed bone bridging on CT. We present preliminary evidence supporting the feasibility of an orthotopic, mid-humeral forelimb allotransplantation model under standard immunosuppression regimen. Further research should validate the immunological, infectious, and functional outcomes of this model.

Efficacy of lysostaphin-coated titanium plates on implant-associated MRSA osteitis in minipigs

PurposeThe growing incidence of implant-associated infections (IAIs) caused by biofilm-forming Staphylococcus aureus in combination with an increasing resistance to antibiotics requires new therapeutic strategies. Lysostaphin has been shown to eliminate this biofilm. Own studies confirm the effectiveness in a murine model. The current study characterizes the effects of lysostaphin-coated plates in an IAI minipig model.MethodsThe femur of 30 minipigs was stabilized with a five-hole plate, a bone defect was created, and in 20 cases methicillin-resistant Staphylococcus aureus was applied. Ten animals served as control group. After 14 days, local debridement, lavage, and plate exchange (seven-hole plate) were performed. Ten of the infected minipigs received an uncoated plate and 10 a lysostaphin-coated plate. On day 84, the minipigs were again lavaged, followed by euthanasia. Bacterial load was quantified by colony-forming units (CFU). Immunological response was determined by neutrophils, as well as interleukins. Fracture healing was assessed radiologically.ResultsCFU showed significant difference between infected minipigs with an uncoated plate and minipigs with a lysostaphin-coated plate (p = 0.0411). The infection-related excessive callus formation and calcification was significantly greater in the infected animals with an uncoated plate than in animals with a lysostaphin-coated plate (p = 0.0164/p = 0.0033). The analysis of polymorphonuclear neutrophils and interleukins did not reveal any pioneering findings.ConclusionThis study confirms the minipig model for examining IAI. Furthermore, coating of plates using lysostaphin could be a promising tool in the therapeutic strategies of IAI. Future studies should focus on coating technology of implants and on translation into a clinical model.

3D POROUS COMPOSITE SCAFFOLDS WITH HIGH CALCIUM PHOSPHATE CONTENT AND ADDITION OF INORGANIC IONS FOR BONE REGENERATION APPLICATIONS

Critical-sized bone defects remain challenging in the clinical setting. Autologous bone grafting remains preferred by clinicians. However, the use of autologous tissue is associated with donor-site morbidity and limited accessibility to the graft tissue. Advances in the development of synthetic bone substitutes focus on improving their osteoinductive properties. Whereas osteoinductivity has been demonstrated with ceramics, it is still a challenge in case of polymeric composites. One of the approaches to improve the regenerative properties of biomaterials, without changing their synthetic character, is the addition of inorganic ions with known osteogenic and angiogenic properties. We have previously reported that the use of a bioactive composite with high ceramic content composed of poly(ethyleneoxide terephthalate)/poly(butylene terephthalate) (1000PEOT70PBT30, PolyActive, PA) and 50% beta-tricalcium phosphate (β-TCP) with the addition of zinc in a form of a coating of the TCP particles can enhance the osteogenic differentiation of human mesenchymal stromal cells (hMSCs) (3). To further support the regenerative properties of these scaffolds, inorganic ions with known angiogenic properties, copper or cobalt, were added to the coating solution.β-TCP particles were immersed in a zinc and copper or zinc and cobalt solution with a concentration of 15 or 45 mM. 3D porous scaffolds composed of 1000PEOT70PBT30 and pure or coated β-TCP were additively manufactured by 3D fibre deposition. The osteogenic and angiogenic properties of the fabricated scaffolds were tested in vitro through culture with hMSCs and human umbilical vein endothelial cells, respectively. The materials were further evaluated through ectopic implantation in an in vivo mini-pig model. The early expression of relevant osteogenic gene markers (collagen-1, osteocalcin) of hMSCs was upregulated in the presence of lower concentration of inorganic ions. Further analysis will focus on the evaluation of ectopic bone formation and vascularisation of these scaffolds after implantation in a mini-pig ectopic intramuscular model.

Xenogenic Engraftment of Human-Induced Pluripotent Stem Cell-Derived Pancreatic Islet Cells in an Immunosuppressive Diabetic Göttingen Mini-Pig Model.

In the development of cell therapy products, immunocompromised animal models closer in size to humans are valuable for enhancing the translatability of in vivo findings to clinical trials. In the present study, we generated immunocompromised type 1 diabetic Göttingen mini-pig models and demonstrated the engraftment of human-induced pluripotent stem cell-derived pancreatic islet cells (iPICs). We induced hyperglycemia with a concomitant reduction in endogenous C-peptide levels in pigs that underwent thymectomy and splenectomy. After estimating the effective in vivo dose of immunosuppressants (ISs) via in vitro testing, we conducted exploratory implantation of iPICs using various implantation methods under IS treatments in one pig. Five weeks after implantation, histological analysis of the implanted iPICs embedded in fibrin gel revealed numerous islet-like structures with insulin-positive cells. Moreover, the area of the insulin-positive cells in the pre-peritoneally implanted grafts was greater than in the subcutaneously implanted grafts. Immunohistochemical analyses further revealed that these iPIC grafts contained cells positive for glucagon, somatostatin, and pancreatic polypeptides, similar to naturally occurring islets. The engraftment of iPICs was successfully reproduced. These data support the observation that the iPICs engrafted well, particularly in the pre-peritoneal space of the newly generated immunocompromised diabetic mini-pigs, forming islet-like endocrine clusters. Future evaluation of human cells in this immunocompromised pig model could accelerate and development of cell therapy products.

Raman spectroscopy of brain and skin tissue in a minipig model of Huntington's disease.

We applied Raman spectroscopy to brain and skin tissues from a minipig model of Huntington's disease. Differences were observed between measured spectra of tissues with and without Huntington's disease, for both brain tissue and skin tissue. There are linked to changes in the chemical composition between tissue types. Using machine learning we correctly classified 96% of test spectra as diseased or wild type, indicating that the test would have a similar accuracy when used as a diagnostic tool for the disease. This suggests the technique has great potential in the rapid and accurate diagnosis of Huntington's and other neurodegenerative diseases in a clinical setting.

The effects of direct polymethylmethacrylate and zirconia-on-Ti-base abutments on peri-implant soft tissue integration: A study in minipigs.

To assess two types of abutment materials routinely used in daily prac-tice-direct polymethyl methacrylate (PMMA) and a zirconia-on-Ti-base abut-ment-and their effects on peri-implant soft tissues and bone remodeling in a mini-pig model. A total of 40 implants were placed in five mini-pigs in a single-stage surgery. Four different types of abutment materials (n = 10 per group) were used: (1) titanium (control); (2) zirconia (control); (3) PMMA (test 1); and (4) Ti-base (zirconia bonded to a titanium framework; test 2). After 3 months of healing, the samples were collected and subjected to nondecalcified histology. The soft tissue dimensions (sulcus, junctional epithelium, and connective tissue attach-ment) were assessed on each abutment mesially and distally, and the distance from the implant margin to the first bone-to-implant contact (BIC) was measured. No statistically significant differences were found among the four groups regarding soft tissue dimensions (P = .21), and a long junctional epithelium (mean: 4.1 mm) and a short connective tissue attachment (mean: 0.3 mm) were found in the majority of abutments. In some samples, the junctional epithelium extended all the way to the bone level. The measured peri-implant bone remodeling was similar in all four groups (P = .25). The present findings indicate that both di-rect PMMA and zirconia-on-Ti-base abutments seem to allow soft tissue integration similar to that of titanium and zirconia abutments. However, clinical studies are war-ranted to either confirm or refute the observed findings and to further investigate the influence of different materials on mucointegration.

Lymphangiogenesis after nonvascularized lymph node transplantation: Lymphangiographic findings in mice and minipigs

The establishment of new connections after NVLNT (non-vascularized lymph node transplantation) is still poorly understood. The purpose of this study was to investigate lymphatic connections after NVLNT using lymphangiography. In a mice model, 40 mice were allocated to undergo NVLNT or sham surgery. On day 21 after NVLNT, the lymphatic vessels were observed on near-infrared fluorescence imaging with indocyanine green. In a minipig model, 12 minipigs underwent NVLNT. On day 14 after NVLNT, the transplanted lymph node and donor site were checked by ultrasound, and minipigs with viable transplanted LNs were allocated to lipiodol lymphangiography or MR lymphangiography groups. Transplanted LN engraftment was examined with immunohistochemical staining. After NVLNT in mice, the signal intensities in the popliteal region at 3 minutes and 5 minutes were higher in the transplanted side than the control side (21.3 ± 8.1 vs. 11.0 ± 4.6 at 3 minutes, 26.7 ± 6.8 vs. 19.7 ± 5.9 at 5 minutes), while in the sham group, there were no significant differences between sides. In minipigs, lipiodol lymphangiography (n = 5) showed Lipiodol accumulation in transplanted LNs with innumerable newly formed lymphatic vessels and lymphovenous shunts. MR lymphangiography (n = 5) showed higher enhancement on the transplanted side compared to the control side. Histology showed successful engraftment of transplanted LNs in 16 out of 20 (80%) mice and 9 out of 12 (75%) minipigs. Omnidirectional lymphangiogenesis forming a dense lymphatic network and spontaneous formation of lymphovenous shunts were shown after NVLNT.

The Yucatan minipig model: A new preclinical model of malnutrition in obese patients with acute or chronic diseases

Background & aimsMalnutrition can develop in patients with obesity suffering from acute or chronic illness or after obesity surgery, promoting sarcopenic obesity. A better understanding of this pathophysiology and the development of new therapeutics for chronic diseases, that are often complicated with malnutrition and obesity, justify the development of new animal experimental models close to the human physiology. This study aims to characterize the effects of obesity and underfeeding on Yucatan obese minipigs, assessing its validity as a preclinical model for obesity-related malnutrition. MethodsSixteen 30-month-old Yucatan minipigs were divided into two groups for 8 weeks: a standard diet group (ST, n=5) and an obesogenic diet group (OB, n=11). After 8 weeks, the OB group was further divided into two sub-groups: a standard diet group (OB-ST, n=5) and a low-calorie/low-protein diet group (OB-LC/LP, n=6) for 8 weeks. Body composition by CT-Scan and blood parameters were monitored, and trapezius muscle biopsies were collected to analyse signaling pathways involved in protein turnover and energy metabolism. ResultsAt W8, OB-ST animals exhibited significantly higher body weight (+37.7%, p=0.03), muscle mass (+24.9%, p=0.02), and visceral fat (+192.0%, p=0.03) compared to ST. Trapezius cross sectional area (CSA) normalized to body weight was lower in OB-ST animals (-15.02%, p=0.017). At W16, no significant changes were observed in protein turnover markers, although REDD1 increased in OB-ST (96.4%, p=0.02). After 8 weeks of low-caloric/low protein diet, OB-LC/LP showed decreased body weight (-9.8%, p=0.03), muscle mass (-6.5%, p=0.03), and visceral fat (-41.5%, p=0.03) compared to OB-ST animals. Trapezius fiber CSA significantly decreased in OB-LC/LP (-36.1%, p<0.0001) and normalized to body weight (-25.4%, p<0.0001), combined to higher ubiquitinated protein content (+38.3%, p=0.02). ConclusionOur data support that the Yucatan minipig model mimics nutritional and skeletal muscle phenotypes observed in obese patients, with or without protein-energy malnutrition. It also reproduces muscle atrophy observed in chronic diseases or post-obesity surgery, making it a promising preclinical model for obesity-related malnutrition.

Tissue properties and respiratory kinematics of the tongue base and soft palate in the obese OSA minipig.

Obesity is a common finding and a major pathogenetic factor in obstructive sleep apnea (OSA) in adults. To understand the mechanisms behind this, the present study investigated the tissue properties and respiratory kinematics of the tongue base and soft palate in the obese OSA minipig model. In 4 verified obese/OSA and 3 non-obese/non-OSA control minipigs, MRI fat-weighted images, ultrasound elastography (USE), and sleep video-fluoroscopy (SVF) were performed to quantify the fat composition, tissue stiffness, and respiratory kinematics of the tongue base and soft palate during sedated sleep. The results indicated that the fat composition gradually increased from the rostral to caudal tongue base, particularly in the posterior 1/3 of the tongue base, regardless of the presence of obesity and OSA. However, this trend was not seen in the soft palate and pharyngeal wall. The pharyngeal wall presented the highest fat composition as compared with the tongue base and soft palate. Overall, obese OSA minipigs showed stiffer tongue tissue than the controls, particularly in the rostral region of the tongue in obese Yucatan minipigs. The respiratory moving ranges of the soft palate were greater in both dorsal-ventral and rostral-caudal directions and during both respiratory and expiratory phases in OSA obese than control minipigs, and the largest moving ranges were seen in OSA obese Panepinto minipigs. The moving range of the tongue base was significantly smaller. These results suggest more fat infiltration in the caudal region of the tongue base regardless of the presence of obesity and/or OSA. The greater tissue stiffness of the tongue in obese OSA minipigs may result from altered neuromuscular drive.

Inflammation-induced subcutaneous neovascularization for the long-term survival of encapsulated islets without immunosuppression.

Cellular therapies for type-1 diabetes can leverage cell encapsulation to dispense with immunosuppression. However, encapsulated islet cells do not survive long, particularly when implanted in poorly vascularized subcutaneous sites. Here we show that the induction of neovascularization via temporary controlled inflammation through the implantation of a nylon catheter can be used to create a subcutaneous cavity that supports the transplantation and optimal function of a geometrically matching islet-encapsulation device consisting of a twisted nylon surgical thread coated with an islet-seeded alginate hydrogel. The neovascularized cavity led to the sustained reversal of diabetes, as we show in immunocompetent syngeneic, allogeneic and xenogeneic mouse models of diabetes, owing to increased oxygenation, physiological glucose responsiveness and islet survival, as indicated by a computational model of mass transport. The cavity also allowed for the in situ replacement of impaired devices, with prompt return to normoglycemia. Controlled inflammation-induced neovascularization is a scalable approach, as we show with a minipig model, and may facilitate the clinical translation of immunosuppression-free subcutaneous islet transplantation.