Corrigendum: Five-Year Outcome After Continuous Flow LVAD With Full-Magnetic (HeartMate 3) Versus Hybrid Levitation System (HeartWare): A Propensity-Score Matched Study From an All-Comers Multicentre Registry

[This corrects the article DOI: 10.3389/ti.2023.11675.].

Five-Year Outcome After Continuous Flow LVAD With Full-Magnetic (HeartMate 3) Versus Hybrid Levitation System (HeartWare): A Propensity-Score Matched Study From an All-Comers Multicentre Registry

Despite the withdrawal of the HeartWare Ventricular Assist Device (HVAD), hundreds of patients are still supported with this continuous-flow pump, and the long-term management of these patients is still under debate. This study aims to analyse 5 years survival and freedom from major adverse events in patients supported by HVAD and HeartMate3 (HM3). From 2010 to 2022, the MIRAMACS Italian Registry enrolled all-comer patients receiving a LVAD support at seven Cardiac Surgery Centres. Out of 447 LVAD implantation, 214 (47.9%) received HM3 and 233 (52.1%) received HVAD. Cox-regression analysis adjusted for major confounders showed an increased risk for mortality (HR 1.5 [1.2-1.9]; p = 0.031), for both ischemic stroke (HR 2.08 [1.06-4.08]; p = 0.033) and haemorrhagic stroke (HR 2.6 [1.3-4.9]; p = 0.005), and for pump thrombosis (HR 25.7 [3.5-188.9]; p < 0.001) in HVAD patients. The propensity-score matching analysis (130 pairs of HVAD vs. HM3) confirmed a significantly lower 5 years survival (81.25% vs. 64.1%; p 0.02), freedom from haemorrhagic stroke (90.5% vs. 70.1%; p < 0.001) and from pump thrombosis (98.5% vs. 74.7%; p < 0.001) in HVAD cohort. Although similar perioperative outcome, patients implanted with HVAD developed a higher risk for mortality, haemorrhagic stroke and thrombosis during 5 years of follow-up compared to HM3 patients.

677 PREDICTION OF RIGHT VENTRICULAR FAILURE AFTER LEFT VENTRICULAR ASSIST DEVICE IMPLANTATION: ROLE OF VASODILATOR CHALLENGE

Pulmonary artery pulsatility index (PAPi) is an indicator of right ventricular (RV) function and an independent predictor of right ventricular failure (RVF) following left ventricular assist device (LVAD) implantation. Administration of vasodilator challenge during right heart catheterization (RHC) could reduce RV workload allowing a better assessment of its functional reserve.

Patients undergoing LVAD implantation at our Institution between May 2013 and August 2021 were enrolled. Only patients who had undergone RHC and vasodilator challenge with sodium nitroprusside were analyzed. We collected all available clinical, instrumental, and haemodynamic parameters, at baseline and after nitroprusside infusion and evaluated potential associations with post-LVAD RVF. Of the 54 patients analyzed, 19 (35%) developed RVF after LVAD implantation. Fractional area change (FAC) (OR: 0.647, CI: 0.481–0.871; P = 0.004), pulmonary artery systolic pressure (PASP)(OR: 0.856, CI: 0.761–0.964; P=0.010), and post-sodium nitroprusside (NTP) PAPi (OR: 0.218, CI: 0.073–0.653; P = 0.006) were independent predictors of post-LVAD RVF. The model combining FAC, PASP, and post-NTP PAPi demonstrated a predictive accuracy of 90.7%. Addition of post-NTP PAPi significantly increased the predictive accuracy of the European Registry for Patients with Mechanical Circulatory Support right-sided heart failure risk score [79.4 vs. 70.4%; area under the curve (AUC): 0.841 vs. 0.724, P = 0.022] and the CRITT score (79.6% vs. 74%; AUC: 0.861 vs. 0.767 P = 0.033).

Post-NTP PAPi has observed to be an independent predictor of RVF following LVAD implantation. Dynamic assessment of PAPi using a vasodilator challenge may represent a method of testing RV functional reserve in candidates for LVAD implantation. Larger and prospective studies are needed to confirm this hypothesis.

Prediction of right ventricular failure after left ventricular assist device implantation: role of vasodilator challenge

AIMS

Pulmonary artery pulsatility index (PAPi) is an indicator of right ventricular (RV) function and an independent predictor of right ventricular failure (RVF) following left ventricular assist device (LVAD) implantation. Administration of vasodilator challenge during right heart catheterization (RHC) could reduce RV workload allowing a better assessment of its functional reserve.

METHODS AND RESULTS

Patients undergoing LVAD implantation at our Institution between May 2013 and August 2021 were enrolled. Only patients who had undergone RHC and vasodilator challenge with sodium nitroprusside were analyzed. We collected all available clinical, instrumental, and haemodynamic parameters, at baseline and after nitroprusside infusion and evaluated potential associations with post-LVAD RVF. Of the 54 patients analyzed, 19 (35%) developed RVF after LVAD implantation. Fractional area change (FAC) (OR: 0.647, CI: 0.481-0.871; P = 0.004), pulmonary artery systolic pressure (PASP) (OR: 0.856, CI: 0.761-0.964; P = 0.010), and post-sodium nitroprusside (NTP) PAPi (OR: 0.218, CI: 0.073-0.653; P = 0.006) were independent predictors of post-LVAD RVF. The model combining FAC, PASP, and post-NTP PAPi demonstrated a predictive accuracy of 90.7%. Addition of post-NTP PAPi significantly increased the predictive accuracy of the European Registry for Patients with Mechanical Circulatory Support right-sided heart failure risk score [79.4 vs. 70.4%; area under the curve (AUC): 0.841 vs. 0.724, P = 0.022] and the CRITT score (79.6% vs. 74%; AUC: 0.861 vs. 0.767 P = 0.033).

CONCLUSION

Post-NTP PAPi has observed to be an independent predictor of RVF following LVAD implantation. Dynamic assessment of PAPi using a vasodilator challenge may represent a method of testing RV functional reserve in candidates for LVAD implantation. Larger and prospective studies are needed to confirm this hypothesis.

Does the distance between residency and implanting center affect the outcome of patients supported by left ventricular assist devices? A multicenter Italian study on radial mechanically assisted circulatory support (MIRAMACS) analysis

BACKGROUND

Patients with LVAD require continuous monitoring and care, and since Implanting Centers (ICs) are more experienced in managing LVAD patients than other healthcare facilities, the distance between patient residency and IC could negatively affect the outcomes.

METHODS

Data of patients discharged after receiving an LVAD implantation between 2010 and 2021 collected from the MIRAMACS database were retrospectively analyzed. The population was divided into two groups: A (n = 175) and B (n = 141), according to the distance between patient residency and IC ≤ or >90 miles. The primary endpoint was freedom from Adverse Events (AEs), a composite outcome composed of death, cerebrovascular accident, hospital admission because of GI bleeding, infection, pump thrombosis, and right ventricular failure. Secondary endpoints were incidences of mortality and complications. All patients were followed-up regularly, according to participating center protocols.

RESULTS

Baseline clinical characteristics and indications for LVAD did not differ between the two groups. The mean duration of support was 25.5 ± 21 months for Group A and 25.7 ± 20 months for Group B (p = 0.79). At 3 years, freedom from AEs was similar between Group A and Group B (p = 0.36), and there were no differences in rates of mortality and LVAD-related complications.

CONCLUSIONS

Distance from the IC does not represent a barrier to successful outcomes as long as regular and continuous follow-up is provided.

C15 DOES THE DISTANCE BETWEEN RESIDENCY AND IMPLANTING CENTER AFFECT THE OUTCOME OF PATIENTS SUPPORTED BY LEFT VENTRICULAR ASSIST DEVICE? A MULTICENTER ITALIAN STUDY ON RADIAL MECHANICALLY ASSISTED CIRCULATORY SUPPORT (MIRAMACS) ANALYSIS

Background

Patients with LVAD require continuous monitoring and care, and since Implanting Centers (IC) are more experienced in managing LVAD patients than other health care facilities, the distance between patient residency and IC could negatively affect the outcomes.

Methods

Data of patients discharged after receiving a LVAD implantation between 2010 and 2021 collected into the MIRAMACS database were retrospectively analyzed. The population was divided into two groups: A (n = 175) and B (n = 141), according to a distance between patient residency and IC ≤ or &gt;of 90 miles. The primary end–point was freedom form Adverse Events (AEs), a composite outcome composed by death, cerebrovascular accident, hospital admission because of GI bleeding, infection, pump thrombosis or right ventricular failure. Secondary end–points were incidences of mortality and complications. All patients were followed–up regularly, according to participating centers protocols, by means of clinical visits, telemonitoring and local care–sharing.

Results

Baseline clinical characteristics and indications for LVAD did not differ between the two groups (Figure 1). Mean duration of support was 25.5±21 months for Group A and 25.7±20 months for Group B (p = 0.79). At 3 years, freedom from AEs was similar between Group A and B (p = 0.32, Figure 2), and there were no differences in rates of mortality and LVAD–related complications (Figure 2).

Conclusions

Distance from the IC does not represent a barrier to successful outcome, as long as regular and continuous follow–up is provided. Telemonitoring could offer several benefits, including early detection of complications and continuous evaluation of patient conditions and data of the pump. Moreover, it seemed to reduce the patient anxiety related to the device, increasing direct communication with the VAD–team. On the other hand, shared health programs with local facilities remains an attractive way to follow–up patient, provided that LVAD specific resources and trained staff are available. The dissemination of LVAD–specific care knowledge is also important to face urgent or emergent needs in the rapidly enlarging population of LVAD patients, by empowering local healthcare facilities.

A Redo Percutaneous Emergency Intervention of Left Ventricular Assist Device Graft Occlusion

In patients with advanced heart failure (HF), left ventricular assist devices (LVADs) have demonstrated to be effective in improving the quality of life and reducing further hospitalizations. Although uncommon, LVAD outflow graft obstruction (OGO) is a potentially life-threatening complication and percutaneous treatment has been proposed as a standard intervention strategy in such cases. We report the case of a 69 year old man admitted due to LVAD failure causing unstable HF. Past medical history included percutaneous intervention on the outflow graft with stent implantation one year before. The patient was under chronic treatment with vitamin K antagonists (VKA). Emergent percutaneous angiography was performed, showing recurrent OGO due to thrombosis located at a kinking site, distally to the previously treated segment. Using distal anchoring technique, a balloon-expandable 10 × 79 mm endoprosthesis (GORE® Viabahn® VBX) was effectively positioned and post-dilated. Final angiography confirmed the patency of the stent implanted one-year before. Despite the procedure succeeding in restoring LVAD function, the patient died due to septic shock ten days after. Our case suggests that recurrent OGO can be effectively treated with percutaneous redo and that long-term stent patency can be achieved with a standard antithrombotic treatment, despite further thrombotic events in other segments of the graft are still possible (especially at the kinking site). Moreover, other noncardiac conditions as infective complications, can dramatically impact the clinical course and lead to unfavorable outcomes.

A new hemodynamic index to predict late right failure in patients implanted with last generation centrifugal pump

BACKGROUND

Right ventricular failure (RVF) is a severe event that increases perioperative mortality after left ventricle assist device (LVAD) implantation. Right ventricular (RV) function is particularly affected by the LVAD speed by altering RV preload and afterload as well as the position of the interventricular septum. However, there are no studies focusing on the relationship between pump speed optimization and risk factors for the development of late RVF.

METHODS

Between 2015 and 2019, 50 patients received LVAD implantation at San Camillo Hospital in Rome. Of these, 38 who underwent pump speed optimization were included. Post-optimization hemodynamic data were collected. We assessed a new Hemodynamic Index (HI), calculated as follows:  HI = MAP × PCWP CVP × RPM set RPM max , to determine the risk of late RVF, which was defined as the requirement for rehospitalization and inotropic support.

RESULTS

Ten patients had late RVF after LVAD implantation. Five patients required diuretic therapy and speed optimization. Three patients required inotropic support with adrenaline 0.05 μg/kg/min. Two patients needed prolonged continuous venovenous hemofiltration and high dose inotropic support. Multivariate analysis revealed that a low HI (odds ratio 11.5, 95% confidence interval, 1.85-65.5, p [.003]) was an independent risk factor for late RVF after LVAD implantation.

CONCLUSION

We demonstrated a low HI being a significant risk factor for the development of RVF after LVAD implantation. We suggest implementing HI as a decision support tool for goal-direct optimization of the device aiming to reduce the burden of late-onset RVF during the follow-up.

Fast myocardial recovery ensured by the combined use of V-A ECMO and IMPELLA CP in cardiogenic shock related to a pheochromocytoma crisis

BACKGROUND

Pheochromocytoma is a rare catecholamine-secreting tumor derived from chromaffin cells in the adrenal glands. An excessive stimulation of cardiac myocytes, when pheochromocytoma 'crisis' occurs, lead to myocardial damage with cardiogenic shock.

AIM OF THE STUDY

We present the case of a A 28-year old female patient admitted with signs of severe cardiogenic shock. She was successfully supported with extracorporeal membrane oxygenation (ECMO) combined with IMPELLA CP heart pump (Abiomed Danvers, MA), for left ventricular unloading. Mechanical circulatory support (MCS) was used to favour myocardial recovery and avoid cardiac remodeling.

RESULTS

A very fast recovery was observed. The ECMO was discontinued after four days. The IMPELLA-CP was safely removed after six days. A completely myocardial recovery was observed.

CONCLUSIONS

Use of MCS might find an indication in case of PCC as a bridge to myocardial recovery.

Hutchinson-Gilford Progeria Syndrome and Severe Aortic Stenosis: A New Hope for Treatment

Hutchinson-Gilford progeria syndrome is an autosomal dominant, rare, fatal pediatric segmental premature aging disease. Cardiovascular and cerebrovascular diseases constitute the major cause of morbidity and mortality. Patients with the syndrome and severe aortic valve stenosis have been described in the literature, and for all of them a strategy of conservative management has been followed. We describe the first successful treatment of a 23-year-old Hutchinson-Gilford progeria syndrome patient with severe aortic stenosis who underwent transapical transcatheter aortic valve replacement.

Percutaneous Aortic Valve Closure in Patient With Left Ventricular Assist Device and Dilated Aortic Annulus

Percutaneous transcatheter intervention for aortic regurgitation secondary to implantation of a continuous-flow left ventricular assist device remains challenging, because of the minimal global experience with these procedures. Two treatment options are available: transcatheter aortic valve replacement, which is not always feasible when a dilated aortic annulus is present, and percutaneous aortic valve occlusion. We report a successful percutaneous closure of the aortic valve using an oversized Amplatzer patent foramen ovale multifenestrated device (St Jude Medical, Saint Paul, MN) to treat aortic regurgitation associated with dilated aortic annulus in a patient with a continuous-flow left ventricular assist device.

Analysis of early and long-term outcomes of acute type A aortic dissection according to the new international aortic arch surgery study group recommendations

To evaluate predictors of early and long-term outcomes of surgical repair of acute Type A aortic dissection. Retrospective single-centre study evaluating patients surgically treated between 1998 and 2013. Clinical follow-up was performed. Complications were classified according to the International Aortic Arch Surgery Study Group recommendations. Statistical analysis included univariate and multivariate analysis of preoperative and operative data. One hundred eighty-five patients were evaluated. The follow-up was complete for 180 patients (97 %). Mean age was 63 years, 82 % had a DeBakey type I aortic dissection, 18 % a type II. Eleven patients (6 %) died intraoperatively, 119 of the remaining (68 %) had postoperative complications. Thirty-day mortality was 21 % (38 patients). Average ICU and hospital stay were 6 and 14 days, respectively. During a mean follow-up time of 6 ± 4 years we observed 44 deaths (31 %). Twenty patients (14 %) needed late thoracic aorta reoperation. Results from the multivariate analysis are as follows. Thirty-day mortality was associated with abdominal pain at presentation (p < 0.01). The incidence of postoperative complications was related to older age at intervention (p < 0.01) and longer cross-clamp time (p < 0.01). Mortality at follow-up was significantly increased by older age at intervention (p < 0.01), with a logarithmic growth after 60 years, female sex (p < 0.01), preoperative limb ischemia (p = 0.02) and DHCA (p < 0.01). The surgical results of type A aortic dissection are affected by age at intervention with a logarithmic increase of late mortality in patients older than 60 years.

Pelvic parameters of sagittal balance in extreme lateral interbody fusion for degenerative lumbar disc disease

There is increasing interest in the use of pelvic indices to evaluate sagittal balance and predict outcomes in patients with spinal disease. Conventional posterior lumbar fusion techniques may adversely affect lumbar lordosis and spinal balance. Minimally invasive fusion of the lumbar spine is rapidly becoming a mainstay of treatment of lumbar degenerative disc disease. To our knowledge there are no studies evaluating the effect of extreme lateral interbody fusion (XLIF) on pelvic indices. Hence, our aim was to study the effect of XLIF on pelvic indices related to sagittal balance, and report the results of a prospective longitudinal clinical study and retrospective radiographic analyses of patients undergoing XLIF in a single centre between January 2009 and July 2011. Clinical outcomes are reported for 30 patients and the retrospective analyses of radiographic data is reported for 22 of these patients to assess global and segmental lumbar lordosis and pelvic indices. Effect of XLIF on the correction of scoliotic deformity was assessed in 15 patients in this series. A significant improvement was seen in the visual analogue scale score, the Oswestry Disability Index and the Short Form-36 at 2months and 6months (p<0.0001). The mean pelvic index was 48.6°±11.9° (± standard deviation, SD) with corresponding mean sacral slopes and pelvic tilt of 32.0°±10.6° (SD) and 18.0°±9.5 (SD), respectively. XLIF did not significantly affect sacral slope or pelvic tilt (p>0.2). Global lumbar lordosis was not affected by XLIF (p>0.4). XLIF significantly increased segmental lumbar lordosis by 3.3° (p<0.0001) and significantly decreased the scoliotic Cobb angle by 5.9° (p=0.01). We found that XLIF improved scoliosis and segmental lordosis and was associated with significant clinical improvement in patients with lumbar degenerative disc disease. However, XLIF did not change overall lumbar lordosis or significantly alter pelvic indices associated with sagittal balance. Long-term follow-up with a larger cohort will be required to further evaluate the effects of XLIF on sagittal balance.

Cardiomyocytes in vitro adhesion is actively influenced by biomimetic synthetic peptides for cardiac tissue engineering

Scaffolds for tissue engineering must be designed to direct desired events such as cell attachment, growth, and differentiation. The incorporation of extracellular matrix-derived peptides into biomaterials has been proposed to mimic biochemical signals. In this study, three synthetic fragments of fibronectin, vitronectin, and stromal-derived factor-1 were investigated for the first time as potential adhesive sequences for cardiomyocytes (CMs) compared to smooth muscle cells. CMs are responsive to all peptides to differing degrees, demonstrating the existence of diverse adhesion mechanisms. The pretreatment of nontissue culture well surfaces with the (Arginine-Glycine-Aspartic Acid) RGD sequence anticipated the appearance of CMs' contractility compared to the control (fibronectin-coated well) and doubled the length of cell viability. Future prospects are the inclusion of these sequences into biomaterial formulation with the improvement in cell adhesion that could play an important role in cell retention during dynamic cell seeding.

CD28-mediated cytotoxicity of YT natural killer cells on B7-positive targets induces rapid necrotic death independent of granule exocytosis

The mechanisms leading to target cell killing by the human NK-like cell line YT2C2 have been studied. YT2C2 cells express CD28 antigen and kill B7-expressing targets by a CD28-mediated mechanism which is inhibited by anti-CD28 mAb (CD28.2). The lysis of B7-negative targets, which are also killed by YT2C2, is insensitive to CD28.2, but can be inhibited by cyclosporin A (CsA). CsA reduces degranulation in YT2C2 as measured by BLT-esterase release assays. A total suppression of B7-negative cell lysis was observed in the presence of EGTA, which blocks both degranulation and perforin polymerization, confirming that lysis of this type of target depends solely upon granule exocytosis. In contrast, an additional extracellular EGTA-resistant component in B7-positive target killing was evidenced. These results were consistently obtained with a panel of B7-positive and B7-negative targets, including a Jurkat subclone transfected to express B7 and its parental cell line. Ca2+-independent killing was completed during the first hour of the cytotoxicity assay, whereas EGTA-sensitive lysis increased throughout the whole incubation time. These two lytic mechanisms used by YT2C2 were found to induce two different modes of cell death. Extracellular Ca2+-dependent killing caused apoptotic death in both B7-positive and B7-negative targets, whereas the EGTA-resistant cytolytic pathway, observed exclusively with B7-positive targets, led to necrosis. CD28 triggering in YT2C2 induces, therefore, an additional mechanism of cell killing, independent of granule exocytosis, the nature of which remains to be identified.

Effects of norcantharidin, a protein phosphatase type-2A inhibitor, on the growth of normal and malignant haemopoietic cells

Cantharidin is a natural toxin that inhibits protein phosphatase type 2A (PP2A) and has antitumour effects in man. We have studied the synthetic analogue, norcantharidin (NCTD), which has less nephrotoxic and phlogogenic side-effects, investigating the effects on the normal haemopoietic system and leukaemia cell growth. Daily intraperitoneal (i.p.) injection of NCTD induced dose and circadian time-dependent transient leucocytosis in normal mice, but did not accelerate bone marrow (BM) regeneration, or have haemopoietic offe-effects following chronic administration. NCTD stimulated the cell cycle progression of granulocyte-macrophage colony-forming cells (GM-CFC), stimulated DNA synthesis and increased the frequency of mitotic cells in short-term human BM cultures. NCTD also stimulated the production of interleukin (IL)-1 beta, colony stimulating activity (CSA) and tumour necrosis factor (TNF)-alpha. Continuous in vitro NCTD treatment, however, inhibited both DNA synthesis and GM-CFC growth. Fluorescence-activated cell sorting (FACS) analysis of DNA profiles and cytological studies in HL-60, K-562 or MRC5V2 (fibroblast) cells indicated that low doses of NCTD accelerated the G1/S phase transition, while higher doses or prolonged incubations inhibited the cell cycle at the G2/M phases or during the formation of postmitotic daughter cells. Electron microscopy revealed that NCTD impaired the neogenesis of chromatin material and nuclear membrane during the M/G1 phase transition in K-562 cells. The biphasic effect of NCTD may be due to inhibition of PP2A activity, which regulates the cell cycle, both at the restriction point and at the G2 and M phases. Our data provide new insight into the cellular and molecular actions of NCTD, and partly explain its therapeutical effects in cancer patients.

The hematon, a morphogenetic functional complex in mammalian bone marrow, involves erythroblastic islands and granulocytic cobblestones

The development of pluripotential hematopoietic stem cells (PHSC) requires the continuous support provided by the bone tissue and bone marrow (BM) stromal cells. The basic rule of spatial and temporal organization of the distinct stromal cells and differentiating hematopoietic cells in the course of development, regenerative morphogenesis, or under homeostasis is still poorly understood. We have identified a cohort of preformed, multicellular aggregates in human BM aspirates that we have called hematons. This study shows that homologous hematon complexes can be isolated from the femoral BM shaft of normal mice. Cytologic analysis showed that both human and mouse hematons contained finely arborized endothelial cells, fibroblasts, preadipocytes, lipid-laden cells, and resident macrophages. This stromal cell web was tightly packed with hematopoietic cells comprising primitive cells with marrow-repopulating ability (MRA); day-8 and -12 colony-forming unit-spleen (CFU-S8 and -S12) in the mouse hematon; and high proliferative potential colony-forming cell (HPP-CFC), burst-forming unit-erythroid (BFU-E), granulocyte-macrophage-CFU (GM-CFU), as well as differentiated postmitotic cell populations in both human and mouse hematons. A cohort of single hematons produced a large, but variable, number of myeloid and erythroid cells, as well as megakaryocytes, in organotypic microculture, indicating the heterogenous growth potential of individual hematons. Each hematon developed into a complex, adherent colony in long-term liquid culture, which involves erythroblastic islands and granulocytic cobblestones. The hematons, isolated from 5-fluorouracil (5-FU)-treated mice, contained more HPP-CFC, BFU-E, and GM-CFU populations than the buffy coat (BC) fraction and produced significantly more CFU than normal hematons in organotypic microcultures. The present results provide further support for our hypothesis that the hematon is a tissue-specific complex structure that plays a critical roles in the maintenance of homeostasis and in the regenerative morphogenesis of mammalian BM.

Spontaneous or imposed circadian changes in plasma concentrations of 5-fluorouracil coadministered with folinic acid and oxaliplatin: relationship with mucosal toxicity in patients with cancer

Pharmacokinetics of total platinum, 5-fluorouracil, l-folinic and d-folinic acid, and 5-methyltetrahydrofolate were studied in plasma from nine patients with advanced colorectal cancer treated with oxaliplatin (20 mg/m2/day), 5-fluorouracil (600 mg/m2/day), and folinic acid (300 mg/m2/day). Drugs were administered with a programmable-in-time pump by continuous infusion for 5 days. We compared two drug delivery schedules: constant rate versus chronomodulated rate with peak of oxaliplatin at 4 pm and peak of 5-fluorouracil and folinic acid at 4 am. In the chronomodulated schedule, plasma concentrations of the drugs paralleled the pump functioning: maximum platinum concentration near 4 pm, and maximum 5-fluorouracil and folate concentrations near 4 am. When drugs were administered at a constant rate, mean plasma concentration of 5-fluorouracil varied in a circadian manner each treatment day, that is, a peak at 4 am (approximately 800 ng/ml) and a trough at 1 pm (approximately 100 ng/ml). Mean plasma levels of total platinum and folate compounds increased over the first 24 hours. Total platinum mean level and that of the inactive d-folinic acid isomer reached a constant plasma concentration, whereas biologically active folates exhibited circadian variation in their plasma concentrations (peak around 7 am, trough near 6 pm, and amplitude approximately 10%). Severe mucositis was exhibited by all four patients on the flat schedule, but only by one on the chronomodulated schedule (p < 0.008). Individual pharmacokinetic and toxicity data showed that patients with circadian rhythms in 5-fluorouracil concentrations were least sensitive to 5-fluorouracil-related toxicity. Thus amplification or induction of such rhythm in 5-fluorouracil exposure may permit dose escalation.

Modulation of bone marrow cell functions in vitro by bestatin (ubenimex)

Bestatin (ubenimex), the microbial leucil-aminopeptidase B inhibitor, has been shown previously to stimulate both interleukin-1 (IL-1) and IL-2 production and to enhance T-cell, as well as macrophage mediated immunoreaction when administered in vivo in mice. Here we show that although Bestatin has no direct growth stimulatory activity, it enhances the growth of GM-CFU populations in semisolide culture and stimulates the cell production in liquide organotypic Hematon cultures in synergy with recombinant human GM-CSF. In long term human bone marrow culture Bestatin accelerated the adipocytic differentiation among colony forming stroma cells (F-CFU). Our data provide further evidences that Bestatin may interact with the hemopoietic cell renewal system at different levels of biological organisation.

Roles for the heliodynamic hormones, all trans retinoic acid and 1 alpha, 25-dihydroxyvitamin D3, in control of the hematopoietic cell cycle

It is now well established that the production of primary hematopoietic cells is controlled at different levels of the biological organization. Bone marrow (BM) stromal cells, the extracellular matrix (ECM), polypeptide hematopoietic growth factors (HGF) as well as endogenous cell-division cycle (CDC) related factors play a dominant role in this control. Recent information suggest that the 2 lipophilic hormones, transRA and 1 alpha,25D3, depending on and/or perhaps mediating solar energy, play a role in the maintenance of BM homeostasis. Here we show that both transRA and 1 alpha,25D3: a) modulate the growth and/or stimulate the adipocytic differentiation of fibroblastic stromal cells (F-CFU); b) inhibit the synthesis and extracellular processing but stimulate the solubilization of matrix collagen; c) modulate the clonal growth of myeloid progenitor cells (GM-CFU) in synergy with HGFs; and d) inhibit the production of lactic acid in standard, normal long-term BM cultures (LTBMC). Comparative analysis of normal, preleukemic and leukemic BM cells in LTBMC indicated a positive correlation between the induction of terminal differentiation and reduced lactate production elicited by transRA or 1 alpha,25D3. These results raise a hypothesis according to which the terminal differentiation induced by the helicodynamic hormones is dependent on the mitochondrial aerobic ATP-generating system whose impairment may be a critical step during the process of leukemic transformation.

Retinoic acid in mono- or combined differentiation therapy of myelodysplasia and acute promyelocytic leukemia

Myelodysplastic preleukemic syndromes (MDPS) and acute promyelocytic leukemia (APL) share a surprising in vivo sensitivity to the hormonally acting 13 cis or all trans retinoic acids (transRA). Here we show that transRA as a monotherapeutic agent induced a stable remission in APL at the third relapse. In MDPS, treatment with prednisone and 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25D3) 13 cis RA induced a long-lasting hematological remission. Initially both patients had an impaired BM microenvironment which regenerated on retinoid therapy as judged by reappearance of the Hematon fraction in the BM aspirates. Our preclinical experiments using long-term liquid BM cultures (LTBMC) indicated that several individual patterns of growth and differentiation responses can be induced by combinations of transRA, 1 alpha,25D3 and hemopoietic growth factors (HGFs). The biological responses may vary from complete clonal extinction to a significant growth stimulation of the leukemic blast cell populations. These results further support the importance of preclinical studies in selecting "good" responders for, and excluding "poor" responders from protocols using differentiation therapy.

Hematon, a multicellular functional unit in normal human bone marrow: structural organization, hemopoietic activity, and its relationship to myelodysplasia and myeloid leukemias

An increasing amount of data provides strong evidence for the complex multifactorial control of primary hemopoietic functions. Here we present a new multicellular functional unit, the Hematon, isolated from the light-density floating fraction of normal human bone marrow (BM) aspirates. The Hematon is organized in a compact, three-dimensional spheroid complex from central adipocytes, fibroblastoid cells, and resident macrophages that compartmentalize myeloid, erythroid, and megakaryocyte progenitor cells and their progenies. The Hematon fraction is more than twofold more abundant in progenitor cells when compared to the mononuclear cell (MNC) fraction as gauged by cytological techniques and by analysis of granulocyte-macrophage colony-forming unit (GM-CFU) populations. Individual Hematons may produce, within 2-3 weeks, up to 50,000 hemopoietic cells of different cell lineages in organotypic microcultures. Recombinant human hematopoietic growth factors interleukin 3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), and macrophage colony-stimulating factor (M-CSF) significantly stimulated the endogenous cell production of some but not all of the individually treated Hematons, indicating the heterogeneity of factor-responsive cells within the Hematon population. Comparative observations of 184 BM aspirates support the hypothesis that the presence of Hematons in a BM aspirate correlates positively with homeostatic blood cell production, because the Hematon was present in normal BM (31/40) and it was rare among patients with myelodysplastic syndromes (15/53), acute myeloblastic leukemia (7/39), and chronic myelocytic leukemia (5/52). We suggest that the Hematon represents a unifying model around which the variability of fundamental BM functions and dysfunctions can be explored.

The differentiation-promoting potential of a cytostatic fluoro-pyranosyl adriamycin analog (FAD 104)

Acute toxicity to the hematopoietic cell renewal system is a critical side effect of most anticancer agents. Here we compared the effects of FAD-104 to those of the parent compound adriamycin (ADM) and of epi-adriamycin (epi-ADM) on the growth and differentiation of normal as well as leukemic human myeloid progenitor cells. FAD-104 was less toxic to myeloid colony-forming cells (GM-CFU) than ADM or epi-ADM. In addition, FAD-104 but not ADM induced a clonal down-grading in both normal and leukemic blast cells, and it stimulated the terminal differentiation of myeloid leukemia cells. Therefore, FAD-104 may be useful in the treatment of some forms of myeloid leukemia.

In vitro induction of CFU-S proliferation by a non viral splenic activity from myeloproliferative sarcoma virus infected mice

The myeloproliferative sarcoma virus (MPSV) induces a myeloproliferative syndrome in DBA/2 mice. It is characterized by a considerable increase in the number (100-fold) and in the concentration (10-fold) of pluripotent hematopoietic stem cells detected in vivo (CFU-S) in the spleens of infected animals. Prior studies have shown the presence of a mixed-colony promoting activity (MPA) in neoplastic spleens. In the presence of a small quantity of erythropoietin, MPA induces the proliferation and differentiation of pluripotent hematopoietic stem cells, detected in vitro (Mix-CFU). We tested the effect of factors produced by neoplastic spleen cells on the proliferation of day 10 CFU-S and their entry into the cell cycle. This was done by comparing the number of day 10 CFU-S present in suspensions of normal bone marrow cells incubated for 2 days on agar underlays containing cells from either normal or neoplastic spleens. Our results show the existence of an activity secreted by cells from the spleens of MPSV-infected animals which starts CFU-S cycling and which is physically distinct from MPSV. The presence of this activity, whose identity with MPA remains to be proven, would enable us to explain the proliferation of CFU-S in the course of the disease.

Myeloproliferative syndrome induced by MPSV in DBA/2 mice: presence of a mixed-colonies promoting activity (MPA) in the spleen

The myeloproliferative syndrome induced by the myeloproliferative sarcoma virus (MPSV) in DBA/2 mice stimulates the proliferation of pluripotent hemopoietic stem cells (HSC) and of progenitors committed toward granulomacrophagic and erythroid cell lines. This stimulation may result from a direct effect of the MPSV on HSC or from an indirect effect via locally secreted factors. Normal isogenic bone marrow cells were incubated in the mixed colony-forming unit system in semisolid medium supplemented with conditioned media obtained after incubating neoplastic spleen cells for 3 days at 37 degrees C. These spleen conditioned media contain an activity that is physically separable from MPSV by ultracentrifugation and which, in the presence of a very low quantity of erythropoietin, can induce in vitro the proliferation and differentiation of pluripotent HSC, detected by this Mix-CFU technique. We termed this activity mixed-colonies promoting activity (MPA). These results suggest that the hyperplasia of the nonlymphoid hematopoietic system in the neoplastic spleen results from an indirect effect of the MPSV on pluripotent HSC via locally secreted factors.