Aging reduces the number of mesenchymal stem cells (MSCs) in the bone marrow which leads to impairment of osteogenesis and subsequent bone loss (osteoporosis). Previous attempts to use systematic MSC transplantation have failed to regenerate bone due to inability of the transplanted MSCs to home to bone. MSCs transplantation may be a therapeutic option to treat bone loss if the cells could be directed to bone and induced to differentiate into osteoblasts. Our research group has developed a novel method to direct transplanted MSCs to bone by creating a compound with high affinity to both the ?4?1 integrin on MSCs (a synthetic peptidomimetic ligand, LLP2A) and bone (alendronate). The resulting conjugate, LLP2A-Ale, significantly increased homing of the transplanted MSCs to bone and underwent osteoblast differentiation in a xenotransplantation model. LLP2A-Ale also increased bone formation and bone mass in young immune competent mice. We have shown that MSCs attach to bone and undergo osteogenic differentiation when they are "directed" to the bone surface. Although LLP2A-Ale is effective in young animals, the compound failed to significantly augment bone formation in aged animals unless it was used in combination with systemic MSC transplantation. Moreover, data on disease model is lacking. Therefore, we propose testing the effectiveness of LLP2A-Ale in directing the transplanted MSCs in augmenting bone formation in animal models of osteoporosis and fracture healing. We hypothesize that LLP2A-Ale will direct the transplanted MSCs to the bone surfaces and facilitate new bone formation in the treatments of severe osteoporosis caused by aging, hormone deficiency or other disorders. To test this hypothesis, we propose the following two aims. 1. To determine the efficacy of LLP2A-Ale, or in the combination with MSC transplantation, in the augmentation of bone formation in animal models of osteoporosis. 2. To determine if LLP2A-Ale alone or in combination with MSCs increases MSC engraftment and accelerates fracture healing. The goal of this project is to test whether we can build new bone as a novel treatment for osteoporosis by using LLP2A-Ale to direct transplanted MSCs to the bone. Our preliminary data suggests that LLP2A-Ale can in fact direct transplanted human MSCs to bone and undergo osteoblast differentiation. This is of enormous importance for using MSCs in the treatment of osteoporosis since the major roadblock has been inefficient homing of MSCs to bone. Our novel approach would be effective in patients with primary osteoporosis induced by estrogen deficiency or advanced aging, and in those with secondary osteoporosis due to medications such as glucocorticoids or chemotherapy. Our lead compound, LLP2-Ale, once tested thoroughly in preclinical studies, has great potential to be taken into clinical practice.

Public Health Relevance

Aged individuals have reduced numbers of mesenchymal stem cells (MSCs) in the bone marrow which leads to impairment of bone forming ability and subsequent bone loss (osteoporosis). MSCs are the cells that can give rise to the osteoblasts, the cells that make bone. Giving extra MSCs to patients with severe osteoporosis or delayed fracture healing would be a good therapeutic option. However, this approach was not successful due to the transplanted MSCs can not readily go to bone. Our research group has developed a novel method to guide the transplanted MSCs to bone by creating a compound with high affinity to both to the MSCs and bone. The goal of this project is to test whether we can build new bone in preclinical studies of bone loss using our lead compound, LLP2A-Ale alone, or in the combination of MSCs transplantation, to increase bone formation and if our approach has the potential to make more bones and stronger bones.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR061366-02
Application #
8534708
Study Section
Skeletal Biology Structure and Regeneration Study Section (SBSR)
Program Officer
Chen, Faye H
Project Start
2012-09-01
Project End
2016-08-31
Budget Start
2013-09-01
Budget End
2014-08-31
Support Year
2
Fiscal Year
2013
Total Cost
$263,340
Indirect Cost
$92,340
Name
University of California Davis
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
047120084
City
Davis
State
CA
Country
United States
Zip Code
95618
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Zhong, Zhendong A; Sun, Weihua; Chen, Haiyan et al. (2015) Inactivation of the Progesterone Receptor in Mx1+ Cells Potentiates Osteogenesis in Calvaria but Not in Long Bone. PLoS One 10:e0139490
Dai, Weiwei; Zhang, HongLiang; Zhong, Zhendong A et al. (2015) β-Ecdysone Augments Peak Bone Mass in Mice of Both Sexes. Clin Orthop Relat Res 473:2495-504
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Zhong, Zhendong A; Sun, Weihua; Chen, Haiyan et al. (2015) Optimizing tamoxifen-inducible Cre/loxp system to reduce tamoxifen effect on bone turnover in long bones of young mice. Bone 81:614-9
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Jia, Junjing; Yao, Wei; Amugongo, Sarah et al. (2013) Prolonged alendronate treatment prevents the decline in serum TGF-β1 levels and reduces cortical bone strength in long-term estrogen deficiency rat model. Bone 52:424-32
Yao, Wei; Guan, Min; Jia, Junjing et al. (2013) Reversing bone loss by directing mesenchymal stem cells to bone. Stem Cells 31:2003-14
Yao, Wei; Dai, Weiwei; Jiang, Jean X et al. (2013) Glucocorticoids and osteocyte autophagy. Bone 54:279-84

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