Patients with severe systemic lupus erythematosus (SLE) refractory to conventional treatment are candidates for autologous hematopoietic stem cell (HSC) transplantation if the intent is to reset the immunologic clock. These patients might be candidates for allotransplantation with (SLE)-resistant major histocompatibility complex (MHC) haplotype-matched HSC if partial or complete replacement of an autoimmune-prone system is the intent. Using lupus-prone New Zealand black ؋ New Zealand white (NZBW) mice, we investigated the use of highly enriched, haplomismatched, allogeneic HSC to prevent development of or to treat established autoimmune pathology. Young NZBW mice receiving purified allogeneic HSC transplants had improved survival, decreased proteinuria, circulating immune complexes, and autoantibodies to nuclear antigens than did untreated mice or mice given NZBW HSCs. NZBW mice with established lupus-like disease that received nonmyeloablative conditioning and transplants of (MHC) haplomismatched allogeneic HSCs also had greatly increased overall survival. Mice that received transplants exhibited stabilization or reversal of their lupus symptoms; stabilized or decreased proteinuria, and a lower frequency of elevated circulating immune complexes or autoantibodies than did control mice. Induction of durable mixed chimerism by transplantation of purified allogeneic HSCs after nonmyeloablative conditioning has the potential to reverse symptoms of established NZBW lupus. (Blood.
Severe neutropenia induced by chemotherapy or conditioning for hematopoietic cell transplantation often results in morbidity and mortality due to infection by opportunistic pathogens. A system has been developed to generate ex vivo-expanded mouse myeloid progenitor cells (mMPCs) that produce functional neutrophils in vivo upon transplantation in a pathogen challenge model. It has previously been demonstrated that transplantation of large numbers of freshly isolated myeloid progenitors from a single donor provides survival benefit in radiation-induced neutropenic mice. In the present work, an ex vivo-expanded and cryopreserved mMPC product generated from an allogeneic donor pool retains protective activity in vivo in a lethal fungal infection model. Infusion of the allogeneic pooled mMPC product is effective in preventing death from invasive Aspergillus fumigatus in neutropenic animals, and protection is dose dependent. Cell progeny from the mMPC product is detected in the bone marrow, spleen, blood, and liver by flow cytometry 1 week postinfusion but is no longer evident in most animals 4 weeks posttransplant. In this model, the ex vivo-generated pooled allogeneic mMPC product (i) expands and differentiates in vivo; (ii) is functional and prevents death from invasive fungal infection; and (iii) does not permanently engraft or cause allosensitization. These data suggest that an analogous ex vivo-expanded human myeloid progenitor cell product may be an effective off-the-shelf bridging therapy for the infectious complications that develop during hematopoietic recovery following hematopoietic cell transplantation or intensive chemotherapy.
Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease. Patients’ refractory to therapy may be considered for hematopoietic stem cell transplantation. Using lupus prone female NZB x NZW (NZBW) mice, we tested the ability of highly enriched, allogeneic HSC to prevent and reverse autoimmune symptoms with FACS purified haplo-identical allogeneic HSC. Ablative conditioning: 92 animals were given lethal TBI (14.5 Gy) and divided among 4 groups (Table 1). Urine and serology tested monthly, final time point before death tabulated. Transplantation with either syngeneic HSC or WBM accelerated disease in these mice, resulting in a rate of death exceeding age matched controls. Allogeneic transplanted mice had significantly greater survival above all groups (p= 0.0243). Proteinuria, elevated levels of circulating immune complexes (CIC), and auto-antibodies to dsDNA, nuclear antigens (ANA) and histones were lower in allo-HSC animals compared to the other ablative conditioning groups (p≤ 0.0001). Overall survival (OS) in allo-HSC animals was still unexceptional, possibly due to regimen related toxicity (TRM). Table 1: Ablative age@TX=75 days Age Matched Control Syngeneic WBM Syngeneic HSC Allogeneic HSC N 15 21 28 28 OS@420 days of age 20% 0% 0% 53% Proteinuria 100% 74% 75% 15% CIC 93% 81% 100% 25% Anti-dsDNA 100% 91% 100% 39% Anti-ANA 100% 86% 93% 39% Anti-Histone 93% 91% 100% 46% NMT conditioning: To determine if we could attenuate disease in NZBW mice already progressing into lupus-like disease with transplantation of allogeneic, purified HSC and reduce TRM, we developed a non-myeloablative conditioning protocol (2x5 Gy TBI + ATG + a-ASIALO-GM1) achieving an average mixed chimerism of 50%. Animals were treated at ~241 days with established symptoms of lupus (Table 2). While the group receiving conditioning alone, had a slight survival advantage over age matched control mice, the transplanted mice had greatly increased OS with 70% living well beyond 500 days of age (>250 days from transplant). Allo-HSC mice showed reversal or stabilization of their lupus symptoms including proteinuria, CIC, dsDNA and histone. Table 2: NMT age@Tx=241 days Age Matched Control Allogeneic HSC Conditioned Only N 10 33 30 OS@500 days of age 0% 70% 0% Proteinuria@Tx 20% 49% 47% Final Proteinuria 100% 39% 67% CIC 67% 50% 74% Anti-dsDNA 85% 15% 44% Anti-Histone 100% 37% 66% Conclusions: Ablative and NMT transplant can treat lupus; OS after NMT exceeds ablative conditioning; Induction of mixed chimerism with purified allogeneic HSC using NMT conditioning treats established lupus. The ability of pure HSC transplant and establishment of durable mixed chimerism to reverse established lupus makes it a reasonable strategy to test in man.
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