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 #
5R01AR061366-03
Application #
8721344
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
2014-09-01
Budget End
2015-08-31
Support Year
3
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of California Davis
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
City
Davis
State
CA
Country
United States
Zip Code
95618
Zhang, Hongliang; Kot, Alexander; Lay, Yu-An E et al. (2017) Acceleration of Fracture Healing by Overexpression of Basic Fibroblast Growth Factor in the Mesenchymal Stromal Cells. Stem Cells Transl Med 6:1880-1893
Kot, Alexander; Zhong, Zhendong A; Zhang, Hongliang et al. (2017) Sex dimorphic regulation of osteoprogenitor progesterone in bone stromal cells. J Mol Endocrinol 59:351-363
Zhong, Zhendong A; Kot, Alexander; Lay, Yu-An E et al. (2017) Sex-Dependent, Osteoblast Stage-Specific Effects of Progesterone Receptor on Bone Acquisition. J Bone Miner Res 32:1841-1852
Mohan, Geetha; Lay, Evan Yu-An; Berka, Haley et al. (2017) A Novel Hybrid Compound LLP2A-Ale Both Prevented and Rescued the Osteoporotic Phenotype in a Mouse Model of Glucocorticoid-Induced Osteoporosis. Calcif Tissue Int 100:67-79
Yao, Wei; Lay, Yu-An Evan; Kot, Alexander et al. (2016) Improved Mobilization of Exogenous Mesenchymal Stem Cells to Bone for Fracture Healing and Sex Difference. Stem Cells 34:2587-2600
Yao, W; Dai, W; Jiang, L et al. (2016) Sclerostin-antibody treatment of glucocorticoid-induced osteoporosis maintained bone mass and strength. Osteoporos Int 27:283-294
Dai, Weiwei; Jiang, Li; Lay, Yu-An Evan et al. (2015) Prevention of glucocorticoid induced bone changes with beta-ecdysone. Bone 74:48-57
Yao, Wei; Lane, Nancy E (2015) Targeted delivery of mesenchymal stem cells to the bone. Bone 70:62-5
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 81:614-619
Dai, Weiwei; Zhang, HongLiang; Zhong, Zhendong A et al. (2015) ?-Ecdysone Augments Peak Bone Mass in Mice of Both Sexes. Clin Orthop Relat Res 473:2495-504

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