An anti-adipocyte monoclonal antibody is cytotoxic to porcine preadipocytes in vitro and depresses the development of pig adipose tissue

Hygiene of housing conditions and proinflammatory signals alter gene expressions in porcine adipose tissues and blood cells

Adipose tissue is an organ with metabolic, endocrine and immune functions. In this tissue, the expressions of genes associated with several metabolic pathways, including lipid metabolism, have been shown to be affected by genetic selection for feed efficiency, an important trait to consider in livestock. We hypothesized that the stimulation of immune system caused by poor hygiene conditions of housing impacts the molecular and cellular features of adipose tissue and that the impact may differ between pigs that diverge in feed efficiency. At the age of 12 weeks, Large White pigs from two genetic lines divergent for residual feed intake (RFI) were housed in two contrasting hygiene conditions (good vs poor). After six weeks of exposure, pigs were slaughtered (n = 36). Samples of blood, subcutaneous (SCAT) and perirenal (PRAT) adipose tissues were collected for cell response and gene expression investigations. The decrease in the relative weight of PRAT was associated with a decline in mRNA levels of FASN, ME, LCN2 and TLR4 (P < 0.05) in pigs housed in poor conditions compared with pigs housed in good conditions for both RFI lines. In SCAT, the expressions of only two key genes (PPARG and TLR4) were significantly affected by the hygiene of housing conditions. Besides, the mRNA levels of both LCN2 and GPX3 were influenced by the RFI line (P < 0.05). Because we suspected an effect of poor hygiene at the cellular levels, we investigated the differentiation of stromal vascular cells isolated from SCAT in vitro in the absence or presence of a pro-inflammatory cytokine, Tumor Necrosis Factor-α (TNF-α). The ability of these cells to differentiate in the absence or presence of TNF-α did not differ among the four groups of animals (P > 0.05). We also investigated the expressions of genes involved in the immune response and lipid metabolism in whole blood cells cultured in the absence and presence of LPS. The hygiene conditions had no effect but, the relative expression of the GPX3 gene was higher (P < 0.001) in high RFI than in low RFI pigs while the expressions of IL-10 (P = 0.027), TGFβ1 (P = 0.023) and ADIPOR2 (P = 0.05) genes were lower in high RFI than in low RFI pigs. Overall, the current study indicates that the hygiene of housing had similar effects on both RFI lines on the expression of genes in adipose tissues and on the features of SCAT adipose cells and whole blood cells in response to TNF-α and LPS. It further demonstrates that the number of genes with expression impacted by housing conditions was higher in PRAT than in SCAT. It suggests a depot-specific response of adipose tissue to the current challenge.

Response of adult stem cell populations to a high-fat/high-fiber diet in skeletal muscle and adipose tissue of growing pigs divergently selected for feed efficiency

PURPOSE

The control of body composition by genetics and dietary nutrients is of the upmost importance for both human and animal physiology. Adult stem cells (aSC) may represent a relevant level of tissue adaptation. The purpose of this study was to determine the impact of macronutrient composition on aSC populations isolated from adipose tissue or muscle in growing pigs.

METHODS

Pigs from two lines divergently selected for feed efficiency were fed ad libitum either a high-fat/high-fiber (HF) diet or a low-fat/low-fiber (LF) diet (n = 6 per line and diet) from 74 to 132 days of age. Stroma vascular cells were isolated from adipose tissue and muscle and characterized with cell surface markers.

RESULTS

In both lines, pigs fed the HF diet exhibited a reduced adiposity (P < 0.001) compared with pigs fed the LF diet. In the four groups, CD90 and PDGFRα markers were predominantly expressed in adipose cells, whereas CD90 and CD56 markers were highly expressed in muscle cells. In adipose tissue, the proportions of CD56+/PDGFRα + and of CD90+/PDGFRα + cells were lower (P < 0.05) in HF pigs than in LF pigs. On the opposite, in muscle, these proportions were higher (P < 0.001) in HF pigs.

CONCLUSION

This study indicates that dietary nutrients affected the relative proportions of CD56+/PDGFRα + cells with opposite effects between muscle and adipose tissue. These cell populations exhibiting adipogenic potential in adipose tissue and myogenic potential in muscle may be a target to modulate body composition.

Tissue-specific responses of antioxidant pathways to poor hygiene conditions in growing pigs divergently selected for feed efficiency

BACKGROUND

Poor hygiene of housing induces a systemic inflammatory response. Because inflammation and oxidative stress are processes that can sustain each other, the ways pigs are able to activate their antioxidant defenses are critical for production performance and health during periods when the immune system is solicited. Selection for production performance can also influence reactive oxygen species (ROS) production and expression levels of genes involved in cellular response to oxidative stress in different tissues. To establish the extent by which poor hygiene and selection for feed efficiency affected redox status, pigs divergently selected for residual feed intake (RFI) were housed in poor or good hygiene during 6 weeks. At the end, blood was collected in all pigs, and half of them were killed for tissue sampling. The remaining pigs were reared in good hygiene conditions during a recovery period of 7-8 weeks.

RESULTS

At week 6, poor hygiene was associated with a lower total antioxidant capacity assessed by plasma ferric reducing ability in all pigs, and with greater plasma levels of hydrogen peroxides in the high RFI pigs (less efficient). Adipose tissue of high RFI pigs exhibited higher activities of catalase and glutathione reductase, and greater thiobarbituric acid reactive substances (TBARS) concentrations when compared with the low RFI pigs (more efficient). Poor hygiene conditions activated the antioxidant enzymes activities (glutathione reductase, superoxide dismutase and catalase) in adipose tissue of both lines, but led to higher ROS production by mature adipocytes isolated from the high RFI pigs only. In liver and muscle, there were only minor changes in antioxidant molecules due to genetics and hygiene conditions. After the resilience period, adipose tissue of pigs previously challenged by poor hygiene maintained higher antioxidant enzyme activities, and for the high RFI line, displayed higher TBARS concentrations.

CONCLUSIONS

Pigs selected for improved feed efficiency showed a lower susceptibility to oxidative stress induced by poor hygiene conditions. This could led to a lower inflammatory response and less impaired growth when these pigs are facing sanitary challenges during the production period.

Autoantibodies Against Perilipin 1 as a Cause of Acquired Generalized Lipodystrophy

Acquired generalized lipodystrophy (AGL) is a rare condition characterized by an altered distribution of adipose tissue and predisposition to develop hepatic steatosis and fibrosis, diabetes, and hypertriglyceridemia. Diagnosis of AGL is based on the observation of generalized fat loss, autoimmunity and lack of family history of lipodystrophy. The pathogenic mechanism of fat destruction remains unknown but evidences suggest an autoimmune origin. Anti-adipocyte antibodies have been previously reported in patients with AGL, although their involvement in the pathogenesis has been poorly studied and the autoantibody target/s remain/s to be identified. Using a combination of immunochemical and cellular studies, we investigated the presence of anti-adipocyte autoantibodies in patients with AGL, acquired partial lipodystrophy, localized lipoatrophy due to intradermic insulin injections or systemic lupus erythematosus. Moreover, the impact of anti-adipocyte autoantibodies from AGL patients was assessed in cultured mouse preadipocytes. Following this approach, we identified anti-perilipin 1 IgG autoantibodies in the serum of patients with autoimmune variety-AGL, but in no other lipodystrophies tested. These autoantibodies altered the ability of perilipin 1 to regulate lipolysis in cultured preadipocytes causing abnormal, significantly elevated basal lipolysis. Our data provide strong support for the conclusion that perilipin 1 autoantibodies are a cause of generalized lipodystrophy in these patients.

Integrated analysis of lncRNA and mRNA expression in rainbow trout families showing variation in muscle growth and fillet quality traits

Muscle yield and quality traits are important for the aquaculture industry and consumers. Genetic selection for these traits is difficult because they are polygenic and result from multifactorial interactions. To study the genetic architecture of these traits, phenotypic characterization of whole body weight (WBW), muscle yield, fat content, shear force and whiteness were measured in ~500 fish representing 98 families from a growth-selected line. RNA-Seq was used to sequence the muscle transcriptome of different families exhibiting divergent phenotypes for each trait. We have identified 240 and 1,280 differentially expressed (DE) protein-coding genes and long noncoding RNAs (lncRNAs), respectively, in fish families exhibiting contrasting phenotypes. Expression of many DE lncRNAs (n = 229) was positively correlated with overlapping, neighboring or distantly located protein-coding genes (n = 1,030), resulting in 3,392 interactions. Three DE antisense lncRNAs were co-expressed with sense genes known to impact muscle quality traits. Forty-four DE lncRNAs had potential sponge functions to miRNAs that affect muscle quality traits. This study (1) defines muscle quality associated protein-coding and noncoding genes and (2) provides insight into non-coding RNAs involvement in regulating growth and fillet quality traits in rainbow trout.

The increasingly complex regulation of adipocyte differentiation

Adipose (AD) tissue development and function relies on the ability of adipocytes to proliferate and differentiate into lipid-containing cells that also have endocrine function. Research suggests that certain conditions can induce AD tissue stem cells to differentiate into various cell types and that the microenvironment of the cell, including the extracellular matrix (ECM), is essential in maintaining cell and tissue function. This review provides an overview of factors involved in the proliferation and differentiation of adipocytes. A brief review of the numerous factors that influence PPARγ, the transcription factor thought to be the master regulator of adipocyte differentiation, provides context of established pathways that regulate adipogenesis. Thought provoking findings from research with hypoxia that is supported by earlier research that vascular development is related to adipogenesis are reviewed. Finally, our understanding of the critical role of the ECM and environment in adipogenesis is discussed and compared with studies that suggest that adipocytes may dedifferentiate and can convert into other cell types.

Age-related changes in the features of porcine adult stem cells isolated from adipose tissue and skeletal muscle

A better understanding of the control of body fat distribution and muscle development is of the upmost importance for both human and animal physiology. This requires a better knowledge of the features and physiology of adult stem cells in adipose tissue and skeletal muscle. Thus the objective of the current study was to determine the type and proportion of these cells in growing and adult pigs. The different cell subsets of stromal vascular cells isolated from these tissues were characterized by flow cytometry using cell surface markers (CD11b, CD14, CD31, CD34, CD45, CD56, and CD90). Adipose and muscle cells were predominantly positive for the CD34, CD56, and CD90 markers. The proportion of positive cells changed with age especially in intermuscular adipose tissue and skeletal muscle where the percentage of CD90(+) cells markedly increased in adult animals. Further analysis using coimmunostaining indicates that eight populations with proportions ranging from 12 to 30% were identified in at least one tissue at 7 days of age, i.e., CD90(+)/CD34(+), CD90(+)/CD34(-), CD90(+)/CD56(+), CD90(+)/CD56(-), CD90(-)/CD56(+), CD56(+)/CD34(+), CD56(+)/CD34(-), and CD56(-)/CD34(+). Adipose tissues appeared to be a less heterogeneous tissue than skeletal muscle with two main populations (CD90(+)/CD34(-) and CD90(+)/CD56(-)) compared with five or more in muscle during the studied period. In culture, cells from adipose tissue and muscle differentiated into mature adipocytes in adipogenic medium. In myogenic conditions, only cells from muscle could form mature myofibers. Further studies are now needed to better understand the plasticity of those cell populations throughout life.

Effect of monoclonal antibody on expression of lipid metabolism related genes in porcine adipocytes

In order to study the mechanism of monoclonal antibody (McAb) against a porcine 40-kDa adipocyte-specific plasma membrane protein in reducing fat deposition, porcine primary adipocytes were treated with the McAb during the process of adipocyte differentiation; its effect on expression of lipid metabolism related genes was investigated. Adipocytes were treated with 1-methyl-3-isobutylmethylxanthine (IDX) plus 10 microg/mL of the McAb or without McAb. The mRNA levels of adipocyte differentiation related genes (PPARgamma and C/EBPalpha), lipid metabolism related genes (FAS, HSL, CPT-1B, DGAT and A-FABP) and adiponectin gene (AdipoQ) were determined using real-time quantitative PCR. The results showed that the differentiated adipocyte number and triglyceride (TG) content in adipocytes treated with the McAb were lower than that in cells without McAb during the whole process of adipocyte differentiation. The McAb significantly reduced mRNA expression of PPARgamma, C/EBPalpha, FAS, DGAT, A-FABP and adiponectin genes, but increased mRNA expression of HSL and CPT-1B genes during the medium and latter stage of adipocyte differentiation. This suggested that the McAb decreased triglycerol accumulation in adipocyte by both inhibiting adipocyte differentiation and regulating lipid metabolism, especially at the medium and latter stage of porcine adipocyte differentiation.

Decreased expression of the IGF-II gene during porcine adipose cell differentiation

IGF-I and IGF-II are known to regulate cell development and recent data suggest a possible role of IGF-II on adipose tissue development. This study was undertaken to examine the IGF system gene expression in porcine differentiating adipocytes. Both adipocytes and stromal-vascular (s/v) cells were isolated from subcutaneous adipose tissue collected from 7-day-old piglets. s/v cells were cultured in chemically defined medium. Compared with isolated adipocytes, IGF-II and IGFBP-5 mRNA levels were very high in freshly isolated s/v cells, whereas IGF-I mRNA levels were lower in s/v cells than in adipocytes. Between day 0 and day 6 of culture, IGF-II and IGFBP-5 gene expression decreased whereas expression levels of late markers of adipocyte differentiation were up-regulated. Cell differentiation was also associated with an increase in the expression of IGF-I, insulin and IGF receptor genes. The current findings suggest that IGF-I and IGF-II have different effects on porcine adipose cell development.

Effects of the monoclonal antibody against porcine 40 kDa adipocyte-specific plasma membrane protein on adipocytes and carcass composition

The effects of the mouse monoclonal antibody against 40 kDa adipocyte-specific plasma membrane protein on porcine adipocytes and carcass composition were investigated in vitro and in vivo. Results revealed that the in vitro complement-mediated cytotoxicity of this monoclonal antibody can lead to adipocyte lysis, remarkable reduction of adipocyte lipid accumulation (P<0.01), and significant decrease of well-differentiated fat cells (P<0.01). Treatment of adipocytes with this antibody alone in vitro did not induce cell lysis, but could lead to noticeable reduction of well-differentiated cells and lipid accumulation (P<0.05) at the pre-adipocyte stage. In vivo, pigs injected with 0.5 mg/kg or 1.0 mg/kg of antibody showed smaller adipocyte sizes (P<0.01) and reduced lipid accumulation of adipocytes (P<0.01). Our results also indicated that pigs intraperitoneally or subcutaneously immunized with 0.5 mg/kg of monoclonal antibody at 15 kg or 1.0 mg/kg antibody at 60 kg had a higher lean meat percentage (P<0.05), larger loin eye area (P<0.05), lower fat meat percentage (P<0.05), less backfat thickness (P<0.05) and smaller leaf fat weight (P<0.05) than the control pigs, but other carcass traits such as caul fat weight, heart weight, liver weight, spleen weight, kidney weight, lung weight, and dressing percentage were not significantly affected. These results suggested that this monoclonal antibody could be applied to restrain excessive fat deposition in porcine production.

Antibody-induced lysis of isolated rat epididymal adipocytes and complement activation in vivo

OBJECTIVE

To identify human monoclonal antibodies selectively binding to human adipocytes and to evaluate their ability to induce lysis of isolated rat adipocytes in vitro and to reduce rat complement levels in vivo.

RESEARCH METHODS AND PROCEDURES

Using phage display technology, human monoclonal antibodies binding to human adipocyte plasma membranes were identified. Three antibodies (Fat 13, Fat 37, and Fat 41) were selected based on their additional cross-reaction with rat adipocytes and reformatted as a rat chimeric IgG2bs. The ability of these antibodies, both singly and in combination, to induce lysis of rat epididymal adipocytes in vitro and the reduction of serum complement levels in vivo in the rat was evaluated.

RESULTS

All antibodies caused similar time- and dose-dependent lysis of isolated rat adipocytes. Calculated mean EC(50) values (maximum percentage of lysis in parentheses) were 0.680 microg/mL (63.2%), 0.546 microg/mL (72.4%), and 0.391 microg/mL (73.7%) for Fat 13, Fat 37, and Fat 41, respectively. Combinations were no more effective than individual antibodies in inducing lysis. Anti-adipocyte antibodies (both singly and in combination) were also similarly effective in vivo. In rats, doses of monoclonal antibody up to 10 mg/kg intraperitoneal generally caused almost complete depletion of serum complement up to 24 hours after dosing recovering to baseline values by day 5.

DISCUSSION

Individual and combinations of monoclonal anti-adipocyte antibodies produced a complement-dependent and concentration-dependent activity to lyse adipocytes in vitro and in vivo as measured by a dramatic depletion in serum complement.

Isolation and tissue profiles of a large panel of phage antibodies binding to the human adipocyte cell surface

Phage display is a powerful technique for the rapid selection and isolation of antibodies to any given target antigen. We have applied this technology to isolate over 100 different human antibodies that bind to antigens expressed in situ on the human adipocyte cell surface. This is a diverse panel of antibodies, as indicated by the V-region sequences. The binding profile of each anti-adipocyte antibody has been characterised using phage antibody immunocytochemistry against a panel of normal human tissues. Although there was some variation in the intensity of the adipocyte staining, each antibody consistently recognised adipocytes, where present, irrespective of the tissue source. In addition, all of the antibodies recognised at least one other cell type other than the adipocyte cell surface. In total, over 50 different tissue-binding profiles were recorded, with the most frequently recognised tissues identified as capillaries or smooth muscle. Extensive tissue binding profiles were generated for some antibodies using a panel of 37 different human tissues. This identified anti-adipocyte antibodies with unexpected profiles, such as FAT.13, which binds only to adipocytes and capillaries in the entire tissue panel. We believe this is the most extensive survey ever undertaken of the human adipocyte cell surface. Moreover, similar methodology could be used to derive complete tissue-binding profiles of antibodies against cell-surface antigens of any cell type. Indeed, by screening antibodies on both normal and diseased tissues, it may be possible to identify antigenic associations between different cell types and the pathologies of many diseases.

Abdominal fat pad mass reduction by in ovo administration of anti-adipocyte monoclonal antibodies in chickens

The effect of in ovo administration of antiadipocyte monoclonal antibodies (MAb) on growth and adipose tissue development in chickens was investigated. In Trial 1, 60 fertilized eggs from layer-type chickens were injected into allantoic circulation with different amounts of MAb against chicken adipocyte plasma membranes (0, 0.05, 0.1, 0.2, and 0.4 mg) on Day 15 of embryogenesis. In Trial 2, 180 fertilized broiler eggs were injected into allantoic circulation with 0.2 mg MAb on Day 15 of embryogenesis. In Trial 1, high doses (0.2 and 0.4 mg) of MAb in in ovo injection reduced (P < or = 0.05) abdominal fat pad weight without affecting total body weight at 42 d of age. Only the highest dose (0.4 mg) significantly reduced hatch rate. In Trial 2, adipose tissue (pectoral, femoral, and abdominal), major organ (heart, liver, and spleen), and total body weights at 14 d of age were not affected by in ovo injection. Hatch success rate of eggs was not significantly different among treatments. However, by 6 wk of age, in ovo injection of MAb significantly reduced (P < or = 0.05) abdominal fat pad weight by more than 28%. This relative fat pad mass reduction occurred without affecting femoral or pectoral fat tissues. Total body weight and feed intake were not affected among treatments. Our experiments demonstrated for the first time that in ovo administration of anti-adipocyte MAb on Day 15 of embryogenesis reduced the chicken abdominal fat pad mass by 42 d of age without affecting growth or body weight.

Inhibition of chicken adipocyte differentiation by in vitro exposure to monoclonal antibodies against embryonic chicken adipocyte plasma membranes

Specific monoclonal antibodies (MAb) against adipocyte precursor antigens were developed. These MAb identified adipocyte precursors and reduced their prominence in primary stromal-vascular (SV) cultures by complement-mediated cytotoxicity or by inhibition of differentiation. Binding of antibodies to chicken adipocyte precursors was confirmed by immunofluorescence visual examination following secondary exposure to fluorescein isothiocyanate-conjugated goat antimouse IgG. Cross-reaction of MAb with muscle, kidney, liver, fibroblasts, and other cell types not containing lipid droplets was not observed in primary cultures. Adipocyte precursors were obtained from 18-d chick embryo adipose tissue by collagenase digestion to investigate complement-mediated cytotoxicity of preadipocytes. Cultures were maintained in Medium 199 with 5% fetal bovine serum (FBS) for 4 d. Subsequently, Medium 199 supplemented with 10% chicken serum initiated adipocyte differentiation. At Day 5 postinoculation, individual or combinations of MAb were administered to preadipocyte cultures; rabbit complement was added 30 min later. After 1 d of incubation, four of the six individual MAb with complement significantly (P < 0.05) reduced the number of fat cell clusters that developed by 40 to 60%. These MAb in the presence of complement also significantly (P < 0.05) reduced mean cell width and apparent cell area or cell cluster area of lipid-containing cells. Neither MAb nor complement alone reduced fat cell cluster number, cell size, or cluster size. Treatment with pools of two and four MAb decreased the total amount of MAb protein required to reduce fat cell cluster number. Four antibodies, alone or in combination, reduced fat cell cluster development in a complement-dependent manner.

Proliferation and differentiation of stromal-vascular cells in primary culture differ between neonatal pigs consuming maternal or formula milk

Proliferation and differentiation of preadipocytes from 7-d-old pigs consuming maternal or formula milk were examined in primary culture of stromal-vascular (s-v) cells derived from subcutaneous adipose tissue. Unsuckled pigs were bottle-fed isoenergetically with colostrum and then sow's milk (SM) or with formula milk alone (F) from birth to 7 d. Isolated cells were exposed to serum-supplemented medium and serum-free medium to determine proliferation and differentiation, respectively. Proliferation estimated between d 3 and 4 of culture was higher (P<0.05) in cells from F than SM pigs. In addition, the number of s-v cells isolated from 1 g of adipose tissue was higher (P<0.01) in F than SM pigs. Variables assessing differentiation were also affected. The percentage of differentiating cells and lipoprotein lipase (LPL) activity were lower (P<0.05) in F than SM pigs, whereas malic enzyme (ME) activity did not differ significantly between the two groups. In conclusion, formula milk increased the number of s-v cells and their capacity for proliferation, whereas the potential for cell differentiation was lower compared with cells from the maternal milk group. Further studies are required to identify the growth and/or nutritional factors that are implicated in the observed differences and to determine whether subsequent development of adipose tissue is affected.

The effect of GH and IGF-I on preadipocytes from Large White and Meishan pigs in primary culture

Proliferation and differentiation of preadipocytes from 7-day-old Large White (LW) and Meishan (MS) pigs were studied in primary culture. The effects of porcine GH (pGH) and IGF-I as well as the expression of GH (GHR) and IGF-I (IGF-IR) receptors mRNA were examined. Preadipocytes were exposed to serum-supplemented and serum-free medium to determine proliferation and differentiation, respectively. Proliferation was higher in MS than in LW pigs. Treatment with pGH (2 nM) or IGF-I (10 nM) resulted in a similar decrease in proliferation in LW and MS pigs. Parameters assessing differentiation and the effects of pGH and IGF-I on differentiation did not differ between the two breeds. The percentage of differentiating cells and LPL and ME activities were markedly reduced by pGH. IGF-I did not reduce differentiation significantly. Both GHR and IGF-IR mRNA were expressed in adipose tissue, adipocytes, preadipocytes, and 6-day-cultured cells from LW and MS pigs. The similar action of pGH and IGF-I on preadipocyte proliferation and differentiation, associated with the similar expression of GHR and IGF-IR mRNA in LW and MS pigs, suggests that the GH/IGF-I axis is not impaired in MS pigs. The difference in preadipocyte proliferation observed between LW and MS pigs could account for their adiposity difference.

Effects of antibodies to adipocytes on body weight, food intake, and adipose tissue cellularity in obese rats

Female Wistar rats were fed on a high fat diet for 18 weeks, during which their energy intake increased by 25% and body weight by 50% due to a doubling of adipose tissue tissue stores. Animals were then treated with increasing doses of a sheep polyclonal antiserum to rat adipocytes on days 1-4 and 7 after which they remained untreated for 14 weeks. Antibody treatment reduced body weight by 10% and the weight of parametrial and subcutaneous adipose tissue by 30-40%. This decrease was explicable entirely in terms of a decrease in the number of adipocytes presumably due to adipocyte lysis. These favourable changes in body fat mass were accompanied by improvement in at least one metabolic factor associated with obesity - serum leptin concentrations were significantly reduced in treated animals compared with high fat controls. Genetically obese Zucker rats also showed decreases in the number of adipocytes after treatment with antibodies but in contrast to diet-induced obese rats, they showed a compensatory increase in adipocyte volume which attenuated the effects on body fat mass. These results demonstrate for the first time, the potential to treat diet-induced obesity with antibodies to adipocytes by producing long-term reductions in the number of adipocytes, with minimal side-effects.